Fire-resistant piping material

ABSTRACT

It is an object to provide a fire-resistant piping material that can be fire-protection measures by itself and is excellent in construction workability. A single-layered fire-resistant piping material according to the present invention is constituted of a fire-resistant resin composition containing heat-expandable graphite in an amount of 1 to 10 parts by weight based on 100 parts by weight of a polyvinyl chloride-based resin. A multilayered fire-resistant piping material according to the present invention includes a tubular fire-resistant expandable layer made of a heat-expandable fire-resistant resin composition and a covering layer covering at least one of the outer surface and the inner surface of the fire-resistant expandable layer, and the fire-resistant expandable layer is formed of a fire-resistant resin composition containing heat-expandable graphite in an amount of 1 to 15 parts by weight based on 100 parts by weight of a polyvinyl chloride-based resin, and the covering layer is formed of a polyvinyl chloride-based resin composition not containing heat-expandable fire-resistant materials.

TECHNICAL FIELD

The present invention particularly relates to a fire-resistant pipingmaterial that is excellent in fire resistance and is used in aconstruction passing through a partition of a building.

BACKGROUND ART

Buildings have fireproof compartments defined depending on the types andspecifications of the buildings. In the fireproof compartments,according to the specifications, flooring materials and wall materialsfor fireproof construction or semi-fireproof construction prescribed bythe Building Standards Act are used. The flooring materials and the wallmaterials for fireproof construction or semi-fireproof constructionprescribed by the Building Standards Act are those defined by theMinister of Land, Infrastructure, Transport and Tourism or certified bythe Minister of Land, Infrastructure, Transport and Tourism, andexamples thereof include ferroconcrete; concrete blocks, brickconstructions, and stone constructions that are reinforced with ironmaterials; iron materials covered with steel mortar or concrete on bothsurfaces thereof; lightweight foamed concrete; precast concrete plates;and laminates of plywood and gypsum board, hard wood chip cement board,or lightweight foamed concrete.

Incidentally, buildings are provided with piping (such as electricalconduits, drain pipes, and ducts). Such piping passes through theabove-mentioned fireproof compartment in some cases.

When a through-hole through which piping or the like passes(hereinafter, referred to as “compartment pass-through portion”) isprovided to the above-mentioned fireproof compartment, occurrence offire may cause a big fire accident within a short period of time by thatthe fire and smoke quickly penetrate from the room where the fireoccurred to the next room having the fireproof compartment therebetweenthrough the compartment pass-through portion.

Therefore, the Building Standards Act establishes that only materialsthat passed a fire-resistant test for compartment pass-through andcertified by the Minister of Land, Infrastructure, Transport and Tourismor evaluated by fire defense can be used as the piping material passingthrough the compartment pass-through portion in a building.

Therefore, the compartment pass-through portion is provided withfire-protection measures for caulking a gap with a noncombustiblematerial such as mortar after installing the piping passing through thecompartment so that no gap is formed between the compartmentpass-through portion and the piping.

When the piping material is a metal, since the piping material itself isheat resistant and noncombustible, a sufficient effect is observed onlyby caulking the gap with a noncombustible material such as mortar, asdescribed above. However, the metal piping has a large weight andtherefore has a problem that the workability in transferring and inconstruction is inferior.

On the other hand, when the piping material is a synthetic resin, thepiping is light in weight, excellent in workability, and easy to bond,compared to the metal piping. The synthetic resin piping has thusvarious merits, but is inferior in heat resistance and fire resistance.Therefore, in fire, the piping material is lost by burning or isdeformed by the heat to generate a gap between the compartmentpass-through portion and the piping material, which may allow the heat,fire, and smoke occurred at one side of the fireproof compartment toreach the other side.

Accordingly, for example, it is employed fire-protection measures inwhich a sheet-like covering material having fire-resistance andexpansibility is wound on the outer surface of the synthetic resinpiping material. As the fire-resistant resin composition constitutingthe sheet-like covering material, proposed are those in which a vinylchloride-based resin is blended with heat-expandable graphite, aninorganic filler, and a plasticizer and also blended with a specificphosphorus compound (for example, refer to Patent Document 1) and thosein which a base resin, such as rubber, a thermoplastic elastomer, or aliquid polymer, is blended with heat-expandable graphite serving as aninorganic expansion agent and also blended with a resin serving as adeformation-preventing resin, such as a polycarbonate resin or apolyphenylene sulfide resin (for example, refer to Patent Document 2).

However, in the fire-protection measures using the sheet-like coveringmaterial, a synthetic resin piping material is temporarily installed,and then the sheet-like covering material is wound to the pipingmaterial at a portion previously determined. Subsequently, the pipingmaterial is supported and fixed, and then the opening is filled backwith mortar. Therefore, the measures has a large number of work unitsand takes a long time and also has a problem that the adjustment of thepiping position after the winding of the sheet-like covering material tothe piping material is difficult.

Accordingly, the above-mentioned problems can be solved by directlyproducing a piping material with a resin composition havingfire-resistance and expansibility, but since the fire-resistant resincomposition in Patent Document 1 contains large amounts of an inorganicfiller and a plasticizer in a vinyl chloride-based resin, the pipingmaterial formed therewith cannot obtain a high mechanical strength thatis an indispensable requirement in a pipe. Furthermore, since thefire-resistant resin composition in Patent Document 2 contains rubber, athermoplastic elastomer, or a liquid polymer as the base resin, thepiping material formed therewith cannot obtain a high mechanicalstrength that is an indispensable requirement in a pipe, as in thefire-resistant resin composition of Patent Document 1.

[Patent Document 1] Japanese Unexamined Patent Application PublicationNo. 2006-348228

[Patent Document 2] Japanese Patent No. 3133683

DISCLOSURE OF INVENTION

The present invention has been proposed in the light of theabove-mentioned problems, and it is an object thereof to provide afire-resistant piping material that can be fire-protection measures byitself.

In order to solve the above-mentioned problems, a single-layeredfire-resistant piping material of the invention according to Claim 1 isconstituted of a fire-resistant resin composition containingheat-expandable graphite in an amount of 1 to 10 parts by weight basedon 100 parts by weight of a polyvinyl chloride-based resin.

A single-layered fire-resistant piping material of the inventionaccording to Claim 2 is constituted of a fire-resistant resincomposition containing heat-expandable graphite having a pH of 1.5 to4.0 in an amount of 1 to 10 parts by weight based on 100 parts by weightof a polyvinyl chloride-based resin.

In a single-layered fire-resistant piping material of the inventionaccording to Claim 3, in the invention according to Claim 2, thefire-resistant resin composition according to Claim 2 contains anadditive for providing heat stability during molding.

In a single-layered fire-resistant piping material of the inventionaccording to Claim 4, in the invention according to Claim 3, at leastone selected from the group consisting of lead-based stabilizers,organic tin-based stabilizers, and higher fatty acid metal salts iscontained as the additive for providing heat stability during molding ata total additive amount of 0.3 to 5.0 parts by weight based on 100 partsby weight of the polyvinyl chloride-based resin.

A single-layered fire-resistant piping material of the inventionaccording to Claim 5, in the invention according to Claim 4, furtherincludes a basic compound as the additive for providing heat stabilityduring molding in a total additive amount of 0.3 to 5.0 parts by weightbased on 100 parts by weight of the polyvinyl chloride-based resin.

A single-layered fire-resistant piping material of the inventionaccording to Claim 6 is constituted of a fire-resistant resincomposition containing heat-expandable graphite having an expansionvolume in the range of 100 to 250 mL/g in an amount of 1 to 10 parts byweight based on 100 parts by weight of a polyvinyl chloride-based resin.

A single-layered fire-resistant piping material of the inventionaccording to Claim 7 is constituted of a fire-resistant resincomposition containing heat-expandable graphite having a 1.3-timeexpansion temperature of 180 to 240° C. in an amount of 1 to 10 parts byweight based on 100 parts by weight of a polyvinyl chloride-based resin.

In a single-layered fire-resistant piping material of the inventionaccording to Claim 8, in the invention according to any one of Claims 1to 7, when the piping material is constructed so as to pass through aflooring material and is subjected to a fire-resistant test (complyingwith ISO 834-1) in which the underside of the floor is heated underconditions that one end of the piping material is exposed to a heatingside by 300 mm from the surface on the heating side of the flooringmaterial and that the other end of the piping material is exposed to anon-heating side by 800 mm from the surface on the non-heating side ofthe flooring material, a pipe inner cross-sectional area S1 at the endof the piping material before burning on the heating side and a pipeinner cross-sectional area S2 at a minimum inner diameter of the pipingmaterial after burning satisfy a relationship of (S2/S1)×100≦50.

The invention according to Claim 9 provides a multilayeredfire-resistant piping material including a tubular fire-resistantexpandable layer made of a heat-expandable fire-resistant resincomposition and a covering layer covering at least one of the outersurface and the inner surface of the fire-resistant expandable layer.The fire-resistant expandable layer is formed of a fire-resistant resincomposition containing heat-expandable graphite in an amount of 1 to 15parts by weight based on 100 parts by weight of a polyvinylchloride-based resin, and the covering layer is formed of a polyvinylchloride-based resin composition not containing heat-expandablefire-resistant materials.

The invention according to Claim 10 provides a multilayeredfire-resistant piping material including a tubular fire-resistantexpandable layer made of a heat-expandable fire-resistant resincomposition and a covering layer covering at least one of the outersurface and the inner surface of the fire-resistant expandable layer.The fire-resistant expandable layer is formed of a fire-resistant resincomposition containing heat-expandable graphite having a pH of 1.5 to4.0 in an amount of 1 to 15 parts by weight based on 100 parts by weightof a polyvinyl chloride-based resin, and the covering layer is formed ofa polyvinyl chloride-based resin composition not containingheat-expandable fire-resistant materials.

In a multilayered fire-resistant piping material of the inventionaccording to Claim 11, in the invention according to Claim 10, thefire-resistant resin composition according to Claim 10 contains anadditive for providing heat stability during molding.

A multilayered fire-resistant piping material of the invention accordingto Claim 12, in the invention according to Claim 11, includes at leastone selected from the group consisting of lead-based stabilizers,organic tin-based stabilizers, and higher fatty acid metal salts as theadditive for providing heat stability during molding in a total additiveamount of 0.3 to 5.0 parts by weight based on 100 parts by weight of thepolyvinyl chloride-based resin.

A multilayered fire-resistant piping material of the invention accordingto Claim 13, in the invention according to Claim 12, further includes abasic compound as the additive for providing heat stability duringmolding in a total additive amount of 0.3 to 5.0 parts by weight basedon 100 parts by weight of the polyvinyl chloride-based resin.

The invention according to Claim 14 provides a multilayeredfire-resistant piping material including a tubular fire-resistantexpandable layer made of a heat-expandable fire-resistant resincomposition and a covering layer covering at least one of the outersurface and the inner surface of the fire-resistant expandable layer.The fire-resistant expandable layer is constituted of a fire-resistantresin composition containing heat-expandable graphite having anexpansion volume in the range of 100 to 250 mL/g in an amount of 1 to 15parts by weight based on 100 parts by weight of a polyvinylchloride-based resin, and the covering layer is constituted of apolyvinyl chloride-based resin composition not containingheat-expandable fire-resistant materials, and the covering layer isconstituted of a polyvinyl chloride-based resin composition notcontaining heat-expandable fire-resistant materials.

The invention according to Claim 15 provides a multilayeredfire-resistant piping material including a tubular fire-resistantexpandable layer formed of a heat-expandable fire-resistant resincomposition and a covering layer covering at least one of the outersurface and the inner surface of the fire-resistant expandable layer.The fire-resistant expandable layer is constituted of a fire-resistantresin composition containing heat-expandable graphite having a 1.3-timeexpansion temperature of 180 to 240° C. in an amount of 1 to 15 parts byweight based on 100 parts by weight of a polyvinyl chloride-based resin,and the covering layer is constituted of a polyvinyl chloride-basedresin composition not containing heat-expandable fire-resistantmaterials.

A multilayered fire-resistant piping material of the invention accordingto Claim 16, in the invention according to any one of Claims 9 to 15,when the piping material is constructed so as to pass through a flooringmaterial and is subjected to a fire-resistant test (complying with ISO834-1) in which the underside of the floor is heated under conditionsthat one end of the piping material is exposed to a heating side by 300mm from the surface on the heating side of the flooring material andthat the other end of the piping material is exposed to a non-heatingside by 800 mm from the surface on the non-heating side of the flooringmaterial, a pipe inner cross-sectional area S1 at the end of the pipingmaterial before burning on the heating side and a pipe innercross-sectional area S2 at a minimum inner diameter of the pipingmaterial after burning satisfy a relationship:

(S2/S1)×100≦50.

A multilayered fire-resistant piping material of the invention accordingto Claim 17, in the invention according to any one of Claims 9 to 16,the covering layer is provided on each of the outer surface and theinner surface of the fire-resistant expandable layer.

In the invention according to any of Claims 1 to 8, 1 to 10 parts byweight of heat-expandable graphite is blended with 100 parts by weightof a polyvinyl chloride-based resin. This is because that when theamount of the heat-expandable graphite is smaller than 1 part by weight,a sufficient heat expansibility cannot be obtained during burning, whichcauses insufficient caulking of the inside of a pipe, ascending of hotair through the inside of the pipe, and a decrease in fire-resistanceperformance. On the other hand, when the amount of the heat-expandablegraphite is larger than 10 parts by weight, the heated composition isthermally expanded too much to maintain the shape, resulting in droppingof the residue to decrease the fire-resistance. Herein, the amount ofthe heat-expandable graphite is preferably 1 to 8 parts by weight andfurther preferably 2 to 7 parts by weight.

In the invention according to any of Claims 9 to 17, 1 to 15 parts byweight of heat-expandable graphite is blended with 100 parts by weightof a polyvinyl chloride-based resin. This is because that when theamount of the heat-expandable graphite is smaller than 1 part by weight,a sufficient heat expansibility cannot be obtained during burning, whichcauses insufficient caulking of the inside of a pipe, ascending of hotair through the inside of the pipe, and a decrease in fire-resistanceperformance. On the other hand, when the amount of the heat-expandablegraphite is larger than 15 parts by weight, the heated composition isthermally expanded too much to maintain the shape, resulting in droppingof the residue to decrease the fire-resistance. Herein, the amount ofthe heat-expandable graphite is preferably 1 to 12 parts by weight andfurther preferably 2 to 10 parts by weight.

The heat-expandable graphite used in the present invention is acrystalline compound maintaining a layer structure of carbon and isobtained by acid treatment of a powder such as natural flake graphite,pyrolytic graphite, or Kish graphite by inserting an inorganic acidbetween layers of the graphite using an inorganic acid such asconcentrated sulfuric acid, nitric acid, or selenic acid and a strongoxidant such as concentrated nitric acid, perchloric acid, perchlorate,permanganate, dichromate, or hydrogen peroxide.

The heat-expandable graphite having a pH of 1.5 to 4.0 is prepared byadjusting the pH after the acid treatment described above. The pHadjustment of the heat-expandable graphite is not particularly limited,but, in the state after acid treatment by inserting an inorganic acidbetween layers of raw material graphite as in above, the pH is usually 1or less. Therefore, for example, the acid-treated graphite is washedwith water for removing the remaining acid on the surface of thegraphite, followed by drying. That is, the pH of the heat-expandablegraphite can be increased by repeating washing with water and drying.

In the invention according to any of Claims 2 to 5 and Claims 10 to 13,heat-expandable graphite that is adjusted to acidic is used. This isbecause that the fire-resistance performance is improved by preventingburning by effectively carbonizing a polyvinyl chloride resin duringburning. This is based on a property of a polyvinyl chloride-based resinthat repeats a hydrogen chloride elimination reaction in the presence ofan acid to generate a flame-retardant carbide. However, when the pH ofheat-expandable graphite is lower than 1.5, the too strong acidity may,for example, cause, corrosion of a molding apparatus. On the other hand,when the pH of heat-expandable graphite is higher than 4.0, the effectof accelerating the carbonization of a polyvinyl chloride-based resin islow, which may cause insufficient fire-resistance performance.Accordingly, it is determined to use heat-expandable graphite having apH of 1.5 to 4.0.

Examples of the polyvinyl chloride-based resin used in the inventionaccording to any of Claims 1 to 17 include polyvinyl chloridehomopolymers; copolymers of vinyl chloride monomers and monomers havingunsaturated bonds that are copolymerizable with the vinyl chloridemonomers; and graft copolymers in which vinyl chloride isgraft-copolymerized with (co)polymers other than vinyl chloride. Thesemay be used alone or in a combination of two or more. In addition, thepolyvinyl chloride-based resin may be chlorinated, according to need.

The monomers having unsaturated bonds that are copolymerizable with thevinyl chloride monomers are not particularly limited, and examplesthereof include α-olefins such as ethylene, propylene, and butylene;vinyl esters such as vinyl acetate and vinyl propionate; vinyl etherssuch as butylvinyl ether and cetylvinyl ether; (meth)acrylic acid esterssuch as methyl (meth)acrylate, ethyl (meth)acrylate, and butyl acrylate;aromatic vinyls such as styrene and α-methyl styrene; and N-substitutedmaleimides such as N-phenyl maleimide and N-cyclohexyl maleimide. Thesemay be used alone or in a combination of two or more.

Any (co)polymer that can graft-(co)polymerize vinyl chloride can be usedfor graft-copolymerizing the vinyl chloride without particularlimitation, and examples thereof include ethylene-vinyl acetatecopolymers, ethylene-vinyl acetate-carbon monoxide copolymers,ethylene-ethyl acrylate copolymers, ethylene-butyl acrylate-carbonmonoxide copolymers, ethylene-methyl methacrylate copolymers,ethylene-propylene copolymers, acrylonitrile-butadiene copolymers,polyurethane, polyethylene chloride, and polypropylene chloride. Thesemay be used alone or in a combination of two or more.

The average degree of polymerization of the polyvinyl chloride-basedresin is not particularly limited, but is preferably 400 to 1600 andmost preferably 600 to 1400, since a low average degree ofpolymerization causes a decrease in physical properties of a moldedarticle, and a high average degree causes an increase in meltingviscosity to make molding difficult. In addition, the above-mentioned“average degree of polymerization” refers to an average degree ofpolymerization measured in conformity with JIS K-6721 “testing methodfor vinyl chloride resin” using a resin sample prepared by dissolving acomposite vinyl chloride-based resin in tetrahydrofuran (THF), filteringthe solution for removing insoluble components, and then removing theTHF in the filtrate by drying.

The polymerization method of the polyvinyl chloride-based resin is notparticularly limited. Any known polymerization method may be employed,and examples thereof include a bulk polymerization method, a solutionpolymerization method, an emulsion polymerization method, and asuspension polymerization method.

The chlorination method of the polyvinyl chloride-based resin is notparticularly limited. Any known chlorination method may be employed, andexamples thereof include thermal chlorination and photochlorination.

The polyvinyl chloride-based resin may be cross-linked or modifiedwithin the range that does not impair the fire-resistance performance asa resin composition. In such a case, a resin that is cross-linked ormodified in advance may be used, or the cross-linking or modificationmay be simultaneously performed when an additive or other component isblended. Alternatively, the cross-linking or modification may beperformed after blending of the additive or other component with theresin. The cross-linking of the resin may be performed by any methodwithout particular limitation, and a usual cross-linking method of apolyvinyl chloride-based resin, such as cross-linking using varioustypes of cross-linking agents or oxides, cross-linking by electron beamirradiation, or a method using a water cross-linking agent, may beemployed.

In the invention according to Claim 4 or 12, the total additive amountof the group consisting of lead-based stabilizers, organic tin-basedstabilizers, and higher fatty acid metal salts is 0.3 to 5.0 parts byweight based on 100 parts by weight of the polyvinyl chloride-basedresin. This is because that when the total additive amount of the groupconsisting of lead-based stabilizers, organic tin-based stabilizers, andhigher fatty acid metal salts is smaller than 0.3 parts by weight, theheat stability of the polyvinyl chloride-based resin is difficult to beensured during molding, which may cause easy generation of carbidesduring molding. On the other hand, when the total additive amount of thegroup consisting of lead-based stabilizers, organic tin-basedstabilizers, and higher fatty acid metal salts is larger than 5.0 partsby weight, the acceleration of the carbonization of the polyvinylchloride-based resin during burning is inhibited, which may causeinsufficient fire-resistance performance.

Examples of the lead-based stabilizers include white lead, basic leadsulfite, tribasic lead sulfate, dibasic lead phosphite, dibasic leadphthalate, tribasic lead maleate, a coprecipitate of silica gel and leadsilicate, dibasic lead stearate, lead stearate, and lead naphthalate.

Examples of the organic tin-based stabilizers include mercaptides suchas dibutyltin mercapto, dioctyltin mercapto, and dimethyltin mercapto;maleates such as dibutyltin maleate, dibutyltin maleate polymers,dioctyltin maleate, and dioctyltin maleate polymers; and carboxylatessuch as dibutyltin mercapto, dibutyltin laurate, and dibutyltin lauratepolymers.

Examples of the higher fatty acid metal salts include lithium stearate,magnesium stearate, calcium stearate, calcium laurate, calciumricinoleate, strontium stearate, barium stearate, barium laurate, bariumricinoleate, cadmium stearate, cadmium laurate, cadmium ricinoleate,cadmium naphthenate, cadmium 2-ethylhexanoate, zinc stearate, zinclaurate, zinc ricinoleate, zinc 2-ethylhexanoate, lead stearate, dibasiclead stearate, and lead naphthenate.

In the invention according to Claim 5 or 13, the amount of the basiccompound is 0.3 to 5.0 parts by weight based on 100 parts by weight ofthe polyvinyl chloride-based resin. This is because that when theadditive amount of the basic compound is smaller than 0.3 parts byweight, the heat stability of the polyvinyl chloride-based resin isdifficult to be ensured during molding, which may cause easy generationof carbides during molding. On the other hand, when the additive amountof the basic compound is larger than 5.0 parts by weight, theacceleration of carbonization of the polyvinyl chloride-based resinduring burning is inhibited, which may cause insufficientfire-resistance performance.

The basic compound is not particularly limited, and examples thereofinclude calcium carbonate, calcium silicate, calcium hydroxide, calciumoxide, magnesium carbonate, magnesium hydroxide, magnesium oxide, bariumcarbonate, aluminum hydroxide, zinc oxide, zinc hydroxide, and ironoxide.

In the invention according to Claim 6 or 14, the term “expansion volumeof the heat-expandable graphite” refers to the volume per gram ofheat-expandable graphite after heat expansion.

The expansion volume of heat-expandable graphite is determined by thefollowing process:

1) One gram of a sample is put in a 500-cc. beaker that is heated inadvance for 20 minutes or more in a heating furnace and is heated in theheating furnace (furnace temperature: 1000° C.);

2) After 30 seconds, the beaker is taken out from the heating furnace;

3) The sample in the beaker is cooled to room temperature;

4) The weight and the volume of the sample after expansion are measured;and

5) The value of (volume of the sample after expansion)/(weight of thesample after the expansion) is calculated.

The expansion volume of heat-expandable graphite varies depending on thetype and amount of the interlayer compound of the heat-expandablegraphite and on the particle diameter of the heat-expandable graphiteitself, and is a very important factor for exhibiting fire-resistance.

In the invention according to Claim 6 or 14, the expansion volume ofheat-expandable graphite is 100 to 250 mL/g. This is because that whenthe expansion volume of heat-expandable graphite is smaller than 100mL/g, the expansion volume is too small to achieve sufficientfire-resistance, which requires a large amount of heat-expandablegraphite for increasing the fire-resistance and may cause defects in,for example, physical properties or molding properties. On the otherhand, when the expansion volume of heat-expandable graphite is largerthan 250 mL/g, the heated composition is thermally expanded too much tomaintain the shape, which may cause dropping of the residue and adecrease in the fire-resistance. Herein, the expansion volume ofheat-expandable graphite is preferably 120 to 230 mL/g and morepreferably 140 to 220 mL/g.

In the invention according to Claim 7 or 15, the 1.3-time expansiontemperature of heat-expandable graphite is a temperature of a heatingfurnace when a sample of heat-expandable graphite is heated for 30minutes in the furnace in which the temperature is kept constant and theexpansion magnification of the sample is 1.3 times or more at thetemperature.

In addition, expansion magnification is defined by (volume of sampleafter heating)/(volume of sample before heating).

The resin temperature during molding refers to the highest temperatureof the resin during melting.

In the invention according to Claim 7 or 15, the 1.3-time expansiontemperature of heat-expandable graphite is 180 to 240° C. This isbecause that when the 1.3-time expansion temperature of heat-expandablegraphite is lower than 180° C., the heat-expandable graphite may expandduring molding, which causes a defect in appearance of a pipe and alsomay decrease the fire-resistance during burning. On the other hand, whenthe 1.3-time expansion temperature of heat-expandable graphite is higherthan 240° C., there is no risk of starting of expansion of theheat-expandable graphite during molding, but thermal decomposition(foaming) of the polyvinyl chloride-based resin progresses duringburning. Therefore, since the heat-expandable graphite expands after areduction in plasticity of the polyvinyl chloride-based resin, thepolyvinyl chloride-based resin may not bear the expansion of theheat-expandable graphite to be broken to pieces.

The fire-resistant test in the invention according to Claim 8 or 16 iscarried out according to an evaluation method of a performance test forpipe passing through, for example, a fireproof compartment, based on therevised Building Standards Act in force on Jun. 1, 2000 (Heisei 12). Theflooring material used was PC (precast concrete) plate (length: 600 mm,width: 1200 mm, thickness: 100 mm), which is a flooring material offireproof construction or semi-fireproof construction prescribed by theBuilding Standards Act.

Examples of the flooring material to be used include, in addition to thePC plate, the followings:

1) A wood frame member in which a gypsum board (thickness: 9.5 mm) isbonded to the upper surface of a structural plywood (thickness: 12 mm)and a reinforced gypsum board (thickness: 15 mm) is bonded to the lowersurface of the plywood;

2) A wood frame member in which a gypsum board (thickness: 12.5 mm) isbonded to the upper surface of a structural plywood (thickness: 12 mm)and two reinforced gypsum boards (thickness: 12.5 mm) are bonded to thelower surface of the plywood;

3) A lightweight foamed concrete (ALC) plate having a thickness of 100mm or more; and

4) A precast concrete (PC) plate having a thickness of 70 mm or more. Inparticular, the ALC plate and the PC plate having a thickness of 100 mmor more are preferred.

The gap between the piping material and the compartment pass-throughportion was caulked with mortar. One end of the piping material wasexposed to a heating side by 300 mm from the surface on the heating sideof the flooring material, and the other end of the piping material wasexposed to a non-heating side by 800 mm from the surface on thenon-heating side of the flooring material.

The furnace used in the fire-resistant test had a structure that canheat one surface of a floor material and can almost uniformly give atemporal change in temperature based on the following Expression 1complying with regulation of ISO 834-1 to all over the entire testsurface of the floor material, when the surface on the heating side ofthe floor material was the test surface.

That is, the fire-resistant test furnace was provided with athermocouple (hereinafter, referred to as “furnace thermocouple”) formeasuring temperature in the furnace at a position apart from the floormaterial by 100 to 300 mm such that one to ten hot junctions werearranged uniformly with respect to the test surface of the floormaterial.

Then, according to the regulation of ISO 834-1, the fire-resistant testfurnace was heated so that the temporal change in temperature(hereinafter, referred to as “heating temperature”) measured by thethermocouple can be expressed by a numerical value represented by thefollowing Expression 1:

T=345 log₁₀(8t+1)+20  (Expression 1)

In Expression 1, T denotes an average temperature (° C.) in the furnace,and t denotes elapsed time (minute) in the test, and the temperature wasmeasured within every one minute period.

Regarding the pipe inner cross-sectional area S1 at the end on theheating side of the piping material before burning, the piping materialis measured for inner diameters at least in two directions beforestarting of the fire-resistance test to calculate the average innerdiameter, and then the pipe inner cross-sectional area S1 is calculated.

Regarding the pipe inner cross-sectional area S2 at the minimum innerdiameter portion of the piping material after burning, after starting ofthe fire-resistance test, when smoke appears from the gap between thecompartment pass-through portion and the piping material on thenon-heating side, the burning in the fire-resistant test furnace isterminated, and then the flooring material panel is immediately removedfrom the fire-resistant furnace. After cooling of the pipe, the caulkedpipe is observed from the heating side to determine the projected areaS2 thereof. The S2 may be measured by any method such as the followings:

a method by image analysis of a photograph taken from the heating side,or

a method by sketching a projected portion on a paper, cutting out thesketched portion and weighing the cut-out paper, and determining the S2by proportional calculation based on the weight of the paper of whichweight per unit area is already known.

When no smoke was observed for 2 hours, the test is terminated after 2hours, and the S2 is measured by the above-mentioned process.

In the invention according to Claim 8 or 16, the value obtained by theExpression of (S2/S1)×100 represents a pipe inner cross-sectional areaproportion (%) after burning. In the invention according to Claim 8 or16, the pipe inner cross-sectional area proportion is 50% or less. Thisis because that when the pipe inner cross-sectional area proportion islarger than 50%, the pass-through portion in a pipe after burning cannotbe effectively caulked, which may not give a desired fire-resistanceperformance.

In the invention according to any of Claims 1 to 17, additives, such asa flame retardant, a stabilizer, a lubricant, a processing aid, animpact modifier, a heat-resistance-improving agent, an antioxidant, alight stabilizer, an ultraviolet absorber, a pigment, a plasticizer, anda thermoplastic elastomer, may be added within a range that does notimpair the physical properties.

As the flame retardant, any flame retardant that increases flameretardancy during burning can be used without particular limitation, andexamples thereof include hydroxides such as aluminum hydroxide andmagnesium hydroxide; hydrotalcite; antimony oxides such as antimonydioxide, antimony trioxide, and antimony pentoxide; molybdenum compoundssuch as molybdenum trioxide, molybdenum disulfide, and ammoniummolybdate; bromine-based compounds such as tetrabromobisphenol A,tetrabromethane, tetrabromethane, tetrabromethane, and tetrabromethane;phosphorus-based compounds such as triphenyl phosphate and ammoniumpolyphosphate; calcium borate; and zinc borate. From the viewpoint ofthe effect of preventing burning of polyvinyl chloride, antimonytrioxide is particularly preferred, because antimony compounds generatehalogenated antimony compounds in the presence of halogenated compoundsunder high temperature conditions and prevent a burning cycle with avery high effect, and the synergetic effect thereof is significant.

By using the flame retardant, the synergetic effect between theheat-insulating effect by the expansion of heat-expandable graphite andthe flame-retarding effect by the flame retardant can more efficientlyimprove the fire-resistance performance during burning. The additiveamount of the flame retardant is not particularly limited, but ispreferably 1 part by weight or more and 20 parts by weight or less basedon 100 parts by weight of the polyvinyl chloride-based resin. When theamount of the flame retardant is less than 1 part by weight, sufficientsynergetic effect may not be obtained. When the amount of the flameretardant is higher than 20 parts by weight, the molding properties andthe physical properties may be significantly decreased.

The stabilizer is not particularly limited, and examples thereof includeheat stabilizers and heat stabilization aids. The heat stabilizers arenot particularly limited, and example thereof include organic tin-basedstabilizers such as dibutyltin mercapto, dioctyltin mercapto,dimethyltin mercapto, dibutyltin mercapto, dibutyltin maleate,dibutyltin maleate polymers, dioctyltin maleate, dioctyltin maleatepolymers, dibutyltin laurate, and dibutyltin laurate polymers;lead-based stabilizers such as lead stearate, dibasic lead phosphate,and tribasic lead sulfate; calcium-zinc-based stabilizers;barium-zinc-based stabilizers; and barium-cadmium-based stabilizers.These may be used alone or in a combination of two or more.

The heat stabilization aids are not particularly limited, and examplesthereof include epoxidized soybean oil, phosphate esters, polyols,hydrotalcite, and zeolite. These may be used alone or in a combinationof two or more.

The lubricant includes an inner lubricant and an outer lubricant.

The inner lubricant is used for reducing the fluid viscosity of amelting resin during a molding process to prevent friction heatgeneration. The inner lubricant is not particularly limited, andexamples thereof include butyl stearate, lauryl alcohol, stearylalcohol, epoxidized soybean oil, glycerin monostearate, stearic acid,and bisamides. These may be used alone or in a combination of two ormore.

The outer lubricant is used for accelerating sliding effect between amelting resin and a metal surface during a molding process. The outerlubricant is not particularly limited, and examples thereof includeparaffin wax, polyolefin wax, ester wax, and montanoic acid wax. Thesemay be used alone or in a combination of two or more.

The processing aid is not particularly limited, and examples thereofinclude acryl-based processing aids such as alkyl acrylate-alkylmethacrylate copolymers having a weight average molecular weight of100000 to 2000000. The acryl-based processing aids are not particularlylimited, and examples thereof include n-butyl acrylate-methylmethacrylate copolymers and 2-ethylhexyl acrylate-methylmethacrylate-butyl methacrylate copolymers. These may be used alone orin a combination of two or more.

The impact modifier is not particularly limited, and examples thereofinclude methyl methacrylate-butadiene-styrene (MBS) copolymers,polyethylene chloride, and acrylic rubber.

The heat-resistance-improving agent is not particularly limited, andexamples thereof include α-methylstyrene-based andN-phenylmaleimide-based resins.

The antioxidant is not particularly limited, and examples thereofinclude phenol-based antioxidants.

The light stabilizer is not particularly limited, and examples thereofinclude hindered amine light stabilizers.

The ultraviolet absorber is not particularly limited, and examplesthereof include salicylic acid ester-based, benzophenone-based,benzotriazole-based, and cyanoacrylate-based ultraviolet absorbers.

The pigment is not particularly limited, and examples thereof includeorganic pigments such as azo-based, phthalocyanine-based, surene-based,and dye lake-based pigments; and inorganic pigments such as oxide-based,molybdenum chromate-based, sulfide/selenide-based, andferrocyanide-based pigments.

The polyvinyl chloride-based resin may contain a plasticizer, but sincethe plasticizer may decrease the heat-resistance and fire-resistance ofa molded article, the amount thereof is preferably small.

The plasticizer is not particularly limited, and examples thereofinclude dibutyl phthalate, di-2-ethylhexyl phthalate, anddi-2-ethylhexyl adipate.

The thermoplastic elastomer is not particularly limited, and examplesthereof include acrylnitrile-butadiene (NBR) copolymers, ethylene-vinylacetate (EVA) copolymers, ethylene-vinyl acetate-carbon monoxide (EVACO)copolymers, vinyl chloride-based thermoplastic elastomers such as vinylchloride-vinyl acetate copolymers and vinyl chloride-vinylidene chloridecopolymers, styrene-based thermoplastic elastomers, olefin-basedthermoplastic elastomers, urethane-based thermoplastic elastomers,polyester-based thermoplastic elastomers, and polyamide-basedthermoplastic elastomers. These thermoplastic elastomers may be usedalone or in a combination of two or more.

The method for mixing the additives with the polyvinyl chloride-basedresin is not particularly limited, and examples thereof include a methodby hot-blending and a method by cold blending.

Examples of the fire-resistant piping material of the present inventioninclude fire-resistant pipes and fire-resistant pipe joints.Furthermore, the fire-resistant piping material of the present inventionis molded with an extruder or an injection molder that is usually used.The type and the screw shape of the molder are not particularly limitedas long as sufficient kneading can be performed, considering the tensilestrength and the impact, and an extruder allowing continuous molding ispreferred.

Since the single-layered fire-resistant piping material of the inventionaccording to Claim 1 is constituted of a fire-resistant resincomposition containing heat-expandable graphite in an amount of 1 to 10parts by weight based on 100 parts by weight of a polyvinylchloride-based resin, the molding properties thereof are excellent. Forexample, the piping material can be continuously produced with high sizeaccuracy using an extruder, an injection molder, or the like.

Furthermore, since the polyvinyl chloride-based resin isself-extinguishing, the burning rate is effectively reduced, and therebythe flame propagation velocity during burning can be suppressed. Inaddition, since the resin forms foam in the beginning of burning, anadvantage that the heat-expandable graphite readily expands is alsoprovided.

Furthermore, since heat-expandable graphite itself hardly burns andthereby exhibits a heat-insulating effect by being expanded by heat, theburning rate is further effectively reduced.

Therefore, the single-layered fire-resistant piping material of thepresent invention has excellent fire-resistance and expansibility initself and thereby can prevent flame and smoke from penetrating to theother side partitioned by the compartment pass-through portion by theexpansion of the piping material itself during burning and the effect ofreducing burning rate.

The single-layered fire-resistant piping material of the inventionaccording to Claim 2 includes a fire-resistant expandable layer made ofa fire-resistant resin composition containing heat-expandable graphitehaving a pH of 1.5 to 4.0 in an amount of 1 to 10 parts by weight basedon 100 parts by weight of a polyvinyl chloride-based resin, and therebyhas the following excellent effects.

That is, since the single-layered fire-resistant piping material of theinvention contains heat-expandable graphite having a PH of 1.5 to 4.0,during burning, not only the acid disposed between layers of theheat-expandable graphite but also the acid remaining on the surface ofthe heat-expandable graphite are discharged. Therefore, the amount ofdischarged acid is larger than that of the neutralized heat-expandablegraphite, and an elimination reaction of hydrogen chloride from thepolyvinyl chloride-based resin is accelerated. Consequently, thepolyvinyl chloride-based resin during burning can be effectivelycarbonized. As a result, during burning, the residue formed by theexpanded heat-expandable graphite and the carbide of the polyvinylchloride-based resin that strongly entwining with each other canreliably caulk the end of the pipe on the heating side.

In addition, since the heat-expandable graphite has a pH in the range of1.5 to 4.0, there is no risk of damaging a molding apparatus for moldingthe piping material.

In the invention according to Claim 3, in the invention according toClaim 2, since the fire-resistant resin composition in Claim 2 containsan additive for providing heat stability during molding, the eliminationreaction of hydrogen chloride from the polyvinyl chloride-based resinduring molding is suppressed to prevent the resin from beingdeteriorated and carbonized during molding.

In the invention according to Claim 4, in the invention according toClaim 3, the additive for providing heat stability during moldingcontains at least one selected from the group consisting of lead-basedstabilizers, organic tin-based stabilizers, higher fatty acid metalsalts, and basic compounds in a total additive amount of 0.3 to 5.0parts by weight based on 100 parts by weight of the polyvinylchloride-based resin. Therefore, the deterioration and carbonization ofthe resin during molding can be prevented by suppressing the eliminationreaction of hydrogen chloride from the polyvinyl chloride-based resinduring molding by any of the following actions 1) to 4):

1) capture and neutralization of hydrogen chloride;

2) substitution with chlorine atoms;

3) capture and inactivation of radicals; and

4) isolation of conjugate double bond.

Furthermore, since the lead-based stabilizers, organic tin-basedstabilizers, and higher fatty acid metal salts are further excellent inheat stability during molding, compared to other additives that provideheat stability during molding, the product yield is high, and also thelong-running continuous operation in extrusion molding is excellent.

In addition, the lead-based stabilizers, the organic tin-basedstabilizers, and the higher fatty acid metal salts provide high moldingstability even if the amount thereof is small. Therefore, since theadditive amounts of these additives, based on the amount of thepolyvinyl chloride-based resin, may be smaller than those of otheradditives that provide heat stability during molding, the tensilestrength and fire-resistance of a pipe are hardly decreased.

In the invention according to Claim 5, in the invention according toClaim 4, a basic compound is further contained as the additive forproviding heat stability during molding in a total additive amount of0.3 to 5.0 parts by weight based on 100 parts by weight of the polyvinylchloride-based resin. Therefore, the heat stability during molding andthe tensile strength and fire-resistance of a pipe can be furtherreliably ensured.

Since the single-layered fire-resistant piping material of the inventionaccording to Claim 6 is constituted of a fire-resistant resincomposition containing heat-expandable graphite having an expansionvolume in the range of 100 to 250 mL/g in an amount of 1 to 10 parts byweight based on 100 parts by weight of the polyvinyl chloride-basedresin, the heat-expandable graphite effectively expands during burning,and the piping material is excellent in maintaining the shape of theresidue. Furthermore, the polyvinyl chloride-based resin repeatsde-hydrochloric acid to accelerate carbonization of the polyvinylchloride-based resin. As a result, strong residue is formed, andexcellent effect of reducing the burning rate is obtained by thesynergetic effect with the heat-expandable graphite.

Since the single-layered fire-resistant piping material of the inventionaccording to Claim 7 is constituted of a fire-resistant resincomposition containing heat-expandable graphite having a 1.3-timeexpansion temperature of 180 to 240° C. in an amount of 1 to 10 parts byweight based on 100 parts by weight of the polyvinyl chloride-basedresin, melting/thermal decomposition (foaming) of the polyvinylchloride-based resin do not progress even if the heat-expandablegraphite has reached the 1.3-time expansion temperature, and theelongation viscosity of the polyvinyl chloride-based resin ismaintained. Therefore, the polyvinyl chloride-based resin effectivelyextends according to the expansion of the heat-expandable graphite toform a fire-resistant expandable layer. Since the polyvinylchloride-based resin is subsequently carbonized, highly excellentfire-resistance can be provided even if the amount of theheat-expandable graphite is small.

In the single-layered fire-resistant piping material of the inventionaccording to Claim 8, in the invention according to any one of Claims 1to 7, when the piping material is constructed so as to pass through aflooring material and is subjected to a fire-resistant test (complyingwith ISO 834-1) in which the underside of the floor is heated under theconditions that one end of the piping material is exposed to a heatingside by 300 mm from the surface on the heating side of the flooringmaterial and that the other end of the piping material is exposed to anon-heating side by 800 mm from the surface on the non-heating side ofthe flooring material, a pipe inner cross-sectional area S1 at the endof the piping material before burning on the heating side and a pipeinner cross-sectional area S2 at a minimum inner diameter of the pipingmaterial after burning satisfy a relationship of (S2/S1)×100≦50.Therefore, the pipe inner cross-sectional area during burning becomes50% or less of the pipe inner cross-sectional area S1 before theburning.

As a result, when the single-layered fire-resistant piping material ofthe present invention is installed so as to pass through the floor, evenif the underside of the floor is heated to 1000° C. or more, the residuedoes not drop from the underside of the floor so that a state that thepipe is almost caulked continues for a long period of time. That is, areduction in the pipe inner cross-sectional area during burning canprevent heat from ascending in the pipe and suppress an increase intemperature of the piping material on the non-heating side with respectto the floor. Therefore, the piping material is inhibited from burningout, and smoke generation on the non-heating side, due to a gap with amortar interface generated by softening of the piping material, can beprevented, resulting in improvements in flame shielding performance,heat shielding performance, and smoke shielding performance.

Thus, the single-layered fire-resistant piping material of the inventionaccording to any of Claims 1 to 8 has excellent fire-resistance andexpansibility in itself and thereby can prevent flame and smoke frompenetrating to the other side partitioned by the compartmentpass-through portion by the expansion of the piping material itselfduring burning and the reduction in burning rate. Therefore, it is notnecessary to dispose other fire-resistant member, which is necessary inthe conventional way, around the piping material.

Furthermore, processes such as marking for confirming positions areunnecessary in temporary pipe fitting during construction, and thesingle-layered fire-resistant piping material is simply inserted intothe compartment pass-through portion. Consequently, the work isconsiderably reduced, and the workability in the construction site isdramatically improved.

Furthermore, in the single-layered fire-resistant piping material of thepresent invention, the pipe outer diameter is smaller than that of aso-called fire-resistant double-layered pipe in which fiber-reinforcedmortar covers the outer circumference of the pipe made of a vinylchloride resin. Therefore, when a plurality of through-holes isprovided, the distances among the through-holes can be small, and alsowhen the pipe is installed under the floor, slope can be easilyobtained. Thus, workability is dramatically improved.

The multilayered fire-resistant piping material of the inventionaccording to any of Claims 9 to 16 includes a covering layer formed of apolyvinyl chloride-based resin composition not containingheat-expandable graphite on at least one of the outer surface and theinner surface of the fire-resistant expandable layer. Therefore, inaddition to the effects of the invention according to any of Claims 1 to8, the multilayered fire-resistant piping material is further excellentin the molding properties and can be continuously produced with highsize accuracy by, for example, injection molding or extrusion molding.

Furthermore, the fire-resistant expandable layer contains a polyvinylchloride-based resin as a main component and thereby has sufficientmechanical strength and chemical proof necessary as a piping material.

In addition, since the base resins of both the fire-resistant expandablelayer and the covering layer constituting the piping material arepolyvinyl chloride-based resins, the affinity between the layers ishigh. Therefore, the layers are tightly adhered to each other at theinterface, resulting in providing of excellent water cutoff performance.Consequently, when the multilayered fire-resistant piping materials ofthe present invention are connected to each other with a pipe joint, thetreatment of the end of the piping material is unnecessary, resulting indramatic improvement in construction workability.

When the outer surface of the fire-resistant expandable layer is coveredwith a covering layer formed of a polyvinyl chloride-based resincomposition not containing a heat-expandable fire-resistant material,the outer circumference surface of the piping material is excellent inadhesion and, for example, can be easily and reliably connected toanother member such as a pipe joint.

When the inner surface of the fire-resistant expandable layer is coveredwith a covering layer formed of polyvinyl chloride-based resincomposition not containing a heat-expandable fire-resistant material,the inner circumference surface of the piping material is smooth toallow fluid to smoothly pass. In addition, since the inner circumferencesurface of the piping material is excellent in chemical proof, thepiping material hardly limits the type of fluid, which allows generalpurpose application.

Since the multilayered fire-resistant piping material of the inventionaccording to Claim 17, in the invention according to any one of Claims 9to 16, includes the covering layer on each of the outer surface and theinner surface of the fire-resistant expandable layer, the outercircumference surface of the piping material is excellent in adhesionand, for example, can be easily and reliably connected to another membersuch as a pipe joint, and also the inner circumference surface of thepiping material is excellent in chemical proof, and thereby the pipingmaterial hardly limits the type of fluid, which allows general purposeapplication.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view of a single-layered fire-resistantpiping material P1 according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a multilayered fire-resistant pipingmaterial P2 according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a multilayered fire-resistant pipingmaterial P3 according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view of a multilayered fire-resistant pipingmaterial P4 according to an embodiment of the present invention.

FIG. 5 is an explanatory drawing simply showing a structure of afire-resistant test furnace X used in a fire-resistant test.

FIG. 6 is an explanatory drawing showing a pipe inner cross-sectionalarea S1 of a piping material P, before burning, of the inventionaccording to Claim 8 or 16.

FIG. 7 is an explanatory drawing showing a pipe inner cross-sectionalarea S2 of the piping material P, after burning, of the inventionaccording to Claim 8 or 16.

FIG. 8 is an explanatory drawing showing the state that a conventionalpiping material P was thermally expanded by heating and could notmaintain the shape to drop the residue.

FIG. 9 is an explanatory drawing schematically showing the state ofburning of a conventional piping material P constructed so as to passthrough a flooring material.

FIG. 10 is an explanatory drawing schematically showing the state ofburning of a piping material P according to the present inventionconstructed so as to pass through a flooring material.

FIG. 11 is an explanatory drawing showing the state of a piping materialP according to the present invention that holds the shape to maintainthe fire resistance after being thermally expanded by heating.

BEST MODES FOR CARRYING OUT THE INVENTION

A single-layered fire-resistant piping material P1 of a first embodimentaccording to the present invention is composed of a fire-resistant resincomposition alone, as shown in FIG. 1.

The present invention will be described in detail with reference toexamples below.

In Examples 1 to 16 and Comparative Examples 1 to 5, the followingmaterials were used:

Vinyl chloride resin (manufactured by Taiyo Vinyl Corp., trade name:“TH1000”);

Heat-expandable graphite (manufactured by Tosoh Corp., trade name:“GREP-EG”);

Calcium carbonate (manufactured by Shiraishi Calcium Kaisha, Ltd., tradename: “Whiton SB”);

Lead-based stabilizer (manufactured by Sakai Chemical Industry Co.,Ltd., trade name: “SL-1000”); and

Lubricant (manufactured by Mitsui Chemicals, Inc., trade name: “Hiwax4202E”).

In Examples 17 to 41 and Comparative Examples 6 to 15, the followingmaterials were used:

Vinyl chloride resin (manufactured by Tokuyama Sekisui Co., Ltd, tradename: “TS1000R”);

Heat-expandable graphite (manufactured by Chuetsu Graphite Works Co.,Ltd., trade name: “SFF”);

Lead-based stabilizer: lead stearate (manufactured by MizusawaIndustrial Chemicals, Ltd., trade name: “StabinexNC18”);

Organic tin-based stabilizer: octyltin mercapto (manufactured by SankyoOrganic Chemicals Co., Ltd., trade name: “ONE-100F”);

Higher fatty acid metal salt: Ca/Zn-based composite stabilizer(manufactured by Sakai Chemical Industry Co., Ltd., trade name:“NWP-6000”);

Basic compound: calcium carbonate (manufactured by Shiraishi CalciumKaisha, Ltd., trade name: “Whiton SB”), magnesium hydroxide(manufactured by Kyowa Chemical Industry Co., Ltd., trade name:“KISUMA5A”);

Hydrotalcite (manufactured by Kyowa Chemical Industry Co., Ltd., tradename: “DHT-4A”);

Epoxidized soybean oil (manufactured by ADEKA Corp., trade name:“Adekacizer O130P”); and

Lubricant (manufactured by Mitsui Chemicals Inc., trade name: “Hiwax4202E”).

The pH of the heat-expandable graphite was confirmed by the followingmethod:

1) A graphite mixture is prepared by adding 25 mL of ion-exchange waterto 5 g of a heat-expandable graphite sample;

2) The resulting graphite mixture is stirred with a glass rod for 30seconds; and

3) After leaving the solution for 20 minutes, the pH of the graphitemixture is measured with a pH meter (manufactured by Horiba, Ltd., tradename: “pH/ION METER F-23”).

The pH of the heat-expandable graphite was adjusted by the followingmethod:

The heat-expandable graphite was put in a beaker, and ion exchange waterwas added thereto, followed by stirring. The acid remaining on thesurface of the heat-expandable graphite was removed by washing, whilethe pH of the graphite mixture was confirmed with the pH meter. Then,the graphite mixture was filtered, followed by drying in a thermostaticchamber to give heat-expandable graphite having a desired pH. When adesired pH was not obtained by washing once, the washing and dryingprocesses were repeated.

In Examples 42 to 57 and Comparative Examples 16 to 18, the followingmaterials were used:

Vinyl chloride resin (manufactured by Tokuyama Sekisui Co., Ltd., tradename: “TS1000R”);

Heat-expandable graphite (expansion volume: 65 mL/g): (manufactured bySanyo Trading Co., Ltd. trade name: “SYZR1003”);

Heat-expandable graphite (expansion volume: 100 mL/g): (grainsize-controlled product);

Heat-expandable graphite (expansion volume: 150 mL/g): (manufactured bySanyo Trading Co., Ltd., trade name: “SYZR1002”);

Heat-expandable graphite (expansion volume: 180 mL/g): (manufactured byChuetsu Graphite Works Co., Ltd., trade name: “SFF”);

Heat-expandable graphite (expansion volume: 190 mL/g): (manufactured bySanyo Trading Co., Ltd., trade name: “SYZR502”);

Heat-expandable graphite (expansion volume: 200 mL/g): (manufactured bySanyo Trading Co., Ltd., trade name: “SYZR802”);

Heat-expandable graphite (expansion volume: 250 mL/g): (grainsize-controlled product);

Heat-expandable graphite (expansion volume: 275 mL/g): (manufactured bySanyo Trading Co., Ltd., trade name: “SYZR322”);

Calcium carbonate (manufactured by Shiraishi Calcium Kaisha, Ltd., tradename: “Whiton SB”);

Organic tin-based stabilizer (manufactured by Sankyo Organic ChemicalsCo., Ltd., trade name: “ONZ-142F”);

Lubricant (manufactured by Mitsui Chemicals Inc., trade name: “Hiwax 220MP”); and

Stearic acid (manufactured by Kao Corp., trade name: “S-30”).

In Examples 58 to 70 and Comparative Examples 19 and 20, the followingmaterials were used:

Vinyl chloride resin (manufactured by Tokuyama Sekisui Co., Ltd., tradename: “TS1000R”);

Heat-expandable graphite (manufactured by Chuetsu Graphite Works Co.,Ltd., trade name: “SFF”, expansion volume: 180 mL/g);

Calcium carbonate (manufactured by Shiraishi Calcium Kaisha, Ltd., tradename: “Whiton SB”);

Lead-based stabilizer (manufactured by Sakai Chemical Industry Co.,Ltd., trade name: “SL-1000”); and

Lubricant (manufactured by Mitsui Chemicals Inc., trade name: “Hiwax4202E”).

In Examples 71 to 75 and Comparative Examples 21 and 22, the followingmaterials were used:

Vinyl chloride resin (manufactured by Taiyo Vinyl Corp., trade name:“TH1000”);

Heat-expandable graphite (1.3-time expansion temperature-controlledproduct);

Lead-based stabilizer (manufactured by Sakai Chemical Industry Co.,Ltd., trade name: “SL-1000”); and

Lubricant (manufactured by Mitsui Chemicals Inc., trade name: “Hiwax4202E”).

Then, the above-mentioned materials were mixed at ratios shown in Tables1 to 14, and each mixture was stirred and mixed in a Henschel mixerhaving a capacity of 200 liters (manufactured by Kawada Industries,Inc.) to give a resin composition. The resulting resin composition wasextrusion molded with a generally used extruder to a test pipingmaterial P to be used for fire-resistance evaluation. The resintemperature during molding for those that are not shown in the Tableswas 180° C.

As shown in FIG. 1, the test piping material P was formed so as to havea length of 1200 mm, an outer diameter of 114 mm, a thickness of 6.6 mm,and a nominal diameter of 100 mm.

Furthermore, test pieces to be used for performance evaluation and heatexpansibility evaluation were produced from the test piping material Pby cutting out a part of the pipe wall of the test piping material P,press-molding the cut-out pipe wall with a load of 200 kgf at 190° C.for 3 minutes to a press plate having a thickness of 3 mm, and cuttingthe press plate into 1-cm square pieces.

A multilayered fire-resistant piping material P2 of a second embodimentaccording to the present invention is constituted of a fire-resistantexpandable layer 11 and an inner side covering layer 12 covering theinner circumference surface of the fire-resistant expandable layer 11,as shown in FIG. 2.

A multilayered fire-resistant piping material P3 of a third embodimentaccording to the present invention is constituted of a fire-resistantexpandable layer 11, an inner side covering layer 12 covering the innercircumference surface of the fire-resistant expandable layer 11, and anouter side covering layer 13 covering the outer circumference surface ofthe fire-resistant expandable layer 11, as shown in FIG. 3.

Furthermore, a multilayered fire-resistant piping material P4 of afourth embodiment according to the present invention is constituted of afire-resistant expandable layer 11 and an outer side covering layer 13covering the outer circumference surface of the fire-resistantexpandable layer 11, as shown in FIG. 4.

The present invention will be described in detail with reference toExamples below.

In Examples 76 to 98 and Comparative Examples 23 to 32, the followingmaterials were used:

Vinyl chloride resin (manufactured by Taiyo Vinyl Corp., trade name:“TH1000”);

Heat-expandable graphite (manufactured by Tosoh Corp., trade name:“GREP-EG”, 1.3-time expansion temperature: 210° C.)

Lead-based stabilizer (manufactured by Sakai Chemical Industry Co.,Ltd., trade name: “SL-1000”);

Lubricant (manufactured by Mitsui Chemicals, Inc., trade name: “Hiwax4202E”);

Calcium carbonate (Shiraishi Calcium Kaisha, Ltd., trade name: “WhitonSB”); and

Ammonium polyphosphate (Sumitomo Chemical Co., Ltd., trade name:“Sumisafe P”).

Examples 99 to 120 and Comparative Examples 33 to 35

Vinyl chloride resin (manufactured by Taiyo Vinyl Corp., trade name:“TH1000”);

Heat-expandable graphite (1.3-time expansion temperature-controlledproduct);

Lead-based stabilizer (manufactured by Sakai Chemical Industry Co.,Ltd., trade name: “SL-1000”);

Lubricant (manufactured by Mitsui Chemicals, Inc., trade name: “Hiwax4202E”); and

Calcium carbonate (manufactured by Shiraishi Calcium Kaisha, Ltd., tradename: “Whiton SB”).

Then, the resulting resin composition was extrusion molded with agenerally used extruder to a test piping material P to be used forfire-resistance evaluation. The resin temperature during molding forthose that are not shown in the Tables was 190° C.

The test piping material P was formed so as to have a length of 1200 mm,an outer diameter of 114 mm, a thickness of 6.6 mm, and a nominaldiameter of 100 mm. The thicknesses of the fire-resistant expandablelayer 11, the inner side covering layer 12, and the outer side coveringlayer 13 were adjusted to those shown in Tables 15 to 20.

Furthermore, test pieces to be used for performance evaluation and heatexpansibility evaluation were produced from the test piping material Pby cutting out a part of the pipe wall of the test piping material P,press-molding the cut-out pipe wall with a load of 200 kgf at 190° C.for 3 minutes to a press plate having a thickness of 3 mm, and cuttingthe press plate into 1-cm square pieces.

Fire-Resistance Evaluation

A fire-resistance test (an evaluation method of fire-resistanceperformance test of the revised Building Standards Act in force on Jun.1, 2000 (Heisei 12), complying with ISO 834-1) was performed using thefire-resistant test furnace X shown in FIG. 5.

As the floor material Y, a precast concrete plate (length: 1200 mm,width: 600 mm, thickness: 100 mm) was used. As the fireproofconstruction method, the gap between the test piping material P and thecompartment pass-through portion R was caulked with mortar.

Furthermore, one end of the test piping material P was exposed to theheating side by 300 mm from the surface on the heating side of theflooring material Y, and the other end of the test piping material P wasexposed to the non-heating side by 800 mm from the surface on thenon-heating side of the flooring material Y.

The inner side wall of the heating chamber Z of the fire-resistant testfurnace X was provided with burners V, V. In addition, in the inside ofthe heating chamber Z, two hot junctions of a furnace thermocouple Qwere installed at positions apart from the flooring material Y by 300 mmso as to be evenly arranged with respect to the test surface of theflooring material. Furthermore, the fire-resistant test furnace X wasequipped with an apparatus (not shown) for measuring pressure in thefurnace.

The period of time (smoke-generating time) after the start of heatinguntil the appearance of smoke from the gap between the compartmentpass-through portion R and the test piping material P was measured. Theappearance of smoke was visually determined. A test piece of whichsmoke-generating time was 130 minutes or more was determined as

(excellent), a test piece of 120 minutes or more was determined as ◯(acceptance), a test piece of 75 minutes or more was determined as Δ,and a test piece of shorter than 75 minutes was determined as x(rejection).

The pipe inner cross-sectional area proportion was determined asfollows:

First, the fire-resistant test furnace X was heated so that the temporalchange in heating temperature could be expressed by a numerical valuerepresented by the aforementioned Expression 1.

Then, the burning of the test piping material P was visually observedthrough the observation window G, and when smoke was observed from thegap between the compartment pass-through portion R and the test pipingmaterial P, the burning of the fire-resistant test furnace X wasterminated.

Then, the degree of caulking of the inside of the test piping material Pafter burning was calculated as the pipe inner cross-sectional areaproportion after burning by the following calculation expression using apipe inner cross-sectional area S1 at the end of the test pipingmaterial P, before burning, on the heating side as shown in FIG. 6 and apipe inner cross-sectional area S2 at a minimum inner diameter of thetest piping material P after burning as shown in FIG. 7.

Pipe inner cross-sectional area proportion after burning ═(S2/S1)×100.

Herein, the pipe inner cross-sectional area S1 was determined bymeasuring inner diameters of a piping material in two directions(orthogonal to each other) before the start of the fire-resistance testand calculating the average inner diameter.

Regarding the pipe inner cross-sectional area S2 at a minimum innerdiameter of the piping material after burning, when smoke appeared onthe non-heating side from the gap between the compartment pass-throughportion and the piping material after the starting of the fire-resistanttest, the burning of the fire-resistant test furnace was terminated, andthen the flooring material panel was immediately removed from thefire-resistant furnace. After cooling the pipe, the caulked pipe wasobserved from the heating side to determine the projected area as theS2.

In the measurement of S2, the minimum inner diameter portion in the pipewas sketched on a paper from a photograph taken from the heating side,the sketched portion was cut out and measured the weight thereof, andthe S2 was proportionally calculated on the basis of the weight and thearea of the paper that were already known.

Regarding the elongated length L of the residue, when smoke appeared onthe non-heating side from the gap between the compartment pass-throughportion and the piping material after the start of the fire-resistanttest, the burning of the fire-resistant test furnace was terminated, andthen the flooring material panel was immediately removed from thefire-resistant furnace. After cooling of the pipe, the elongated lengthL orthogonal to the surface on the heating-side of the flooring materialwas measured.

When no smoke was observed for 2 hours, the fire-resistant test wasterminated after 2 hours, and the pipe inner cross-sectional area S2 andthe elongated length L of the residue were measured by theabove-mentioned processes.

Performance Evaluation

The resulting test pieces were subjected to a tensile test (evaluationtemperature: 23° C.) regulated in JIS K7113 for determining whetherperformance required as a pipe is satisfied.

In order to determine whether practical performance required as a pipeis satisfied, a test piece having a tensile strength of 45 MPa or moreat 23° C. was determined as

(excellent), a test piece of 30 MPa or more was determined as ◯(acceptance), and a test piece of less than 30 MPa was determined as x(rejection).

Molding Property Evaluation

A sample that could be extrusion molded and had a satisfactory pipeappearance in appearance visual observation was determined as ◯(acceptance), and a sample that could not be extrusion molded wasdetermined as x (rejection). A sample that had abnormality in pipeappearance was determined as Δ.

Apparatus Corrosive Evaluation

After conducted manufacturing for three hours, the apparatus was leftfor three days. Then, the metal hopper portion of the raw materialfeeding portion was visually observed for investigating the degree ofcorrosion. When no abnormality was observed, it was determined as ◯(acceptance), and when red rust was observed, it was determined as x(rejection).

Extrusion Molding Stability Evaluation

During continuous operation for three hours, the resin compositiondischarged from the tip of an extruder was visually confirmed. A case ofno carbonization and no burning (yellowing), it was determined as

(excellent), a case of no carbonization, it was determined as ◯(acceptance), and a case of carbonization, it was determined as x(rejection).

Heat Expansibility Evaluation

The test pieces were subjected to a fire-resistant test. The test wasperformed by, first, putting the test pieces in an electric furnaceheated to 500° C., leaving them for 40 minutes, then taking out the testpieces from the furnace and cooling them, and then measuring thethicknesses of the test pieces.

When the thickness (thickness after expansion) of a test piece after thefire-resistant test was 4 mm or more, the test piece was accepted, andwhen the thickness was smaller than 4 mm, the test piece was rejected.

TABLE 1 Comparative Comparative Comparative Example 1 Example 2 Example1 Example 2 Example 3 Blend Vinyl chloride resin part 100 100 100 100100 component Heat-expandable part 1 10 0 12 0 graphite Calciumcarbonate part 1 1 1 1 5 Lead-based part 2 2 2 2 2 stabilizer Lubricantpart 0.5 0.5 0.5 0.5 0.5 Fire-resistance Smoke-generating min 120 120 5545 60 evaluation time ◯ ◯ X X X Performance Tensile strength MPa 52 4553 43 51 evaluation (MPa)

◯

Molding property evaluation ◯ ◯ ◯ ◯ ◯

TABLE 2 Example Example Example Example 3 Example 4 Example 5 Example 6Example 7 Example 8 Example 9 10 11 12 Blend Vinyl part 100 100 100 100100 100 100 100 100 100 compo- chloride nent resin Heat- part 5 5 5 5 55 5 5 5 5 expand- able graphite Calcium part 1 2 5 6 12.5 25 37.5 50 060 carbonate Lead- part 2 2 2 2 2 2 2 2 2 2 based stabilizer Lubricantpart 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Fire- Smoke- min 120 130130 120 120 120 120 120 110 120 resistance generating ◯

◯ ◯ ◯ ◯ ◯ Δ ◯ evaluation time Perfor- Tensile MPa 49 48 47 47 45 40 3632 49 28 mance strength

◯ ◯ ◯

X evaluation Molding ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ property evaluation

TABLE 3 Comparative Comparative Example 13 Example 14 Example 15 Example16 Example 4 Example 5 Blend Vinyl chloride resin part 100 100 100 100100 100 component Heat-expandable part 1 4 7 10 0 12 graphite Calciumcarbonate part 40 40 40 40 40 40 Lead-based part 2 2 2 2 2 2 stabilizerLubricant part 0.5 0.5 0.5 0.5 0.5 0.5 Fire-resistance Smoke-generatingmin 120 120 120 120 72 96 evaluation time ◯ ◯ ◯ ◯ X Δ PerformanceTensile strength MPa 38 36 33 31 39 29 evaluation ◯ ◯ ◯ ◯ ◯ X Molding ◯◯ ◯ ◯ ◯ ◯ property evaluation

Experimental Results

As shown in Table 1, since heat-expandable graphite was not used inComparative Examples 1 and 3, the smoke-generating time was short, andthereby the samples were rejected in the fire-resistance evaluation. InComparative Example 2, since the blending ratio of heat-expandablegraphite was too large, the smoke-generating time was short, and therebythe sample was rejected in the fire-resistance evaluation.

Furthermore, as shown in Table 3, since heat-expandable graphite was notused in Comparative Example 4, the smoke-generating time was short, andthereby the sample was rejected in the fire-resistance evaluation. InComparative Example 5, since the blending ratio of heat-expandablegraphite was too large, the smoke-generating time did not reach 120minutes.

Therefore, it was well confirmed that in order to obtain asingle-layered fire-resistant piping material that satisfies all thefire-resistance evaluation, performance evaluation, and molding propertyevaluation requirements, heat-expandable graphite is required to becontained in the range of 1 to 10 parts by weight based on 100 parts byweight of the vinyl chloride resin.

Furthermore, samples in Examples 4 and 5 in Table 2 were furtherexcellent than those in Examples 3 and 6 to 10 in fire-resistance andtensile strength. Therefore, it was confirmed that when a single-layeredfire-resistant piping material contains heat-expandable graphite andalso an inorganic filler in the ranges of 1 to 10 parts by weight and 2to 5 parts by weight, respectively, based on 100 parts by weight of thevinyl chloride resin, a pipe being further well-balanced in any of thefire-resistance, tensile strength, and molding properties can beobtained.

Incidentally, when the amount of the heat-expandable graphite was largerthan 10 parts by weight, the heated composition was thermally expandedtoo much to maintain the shape, resulting in dropping of the residue 2,as shown in FIG. 8.

TABLE 4 Example Example Example Example Comparative ComparativeComparative Comparative 17 18 19 20 Example 6 Example 7 Example 8Example 9 Blend component Vinyl chloride part 100 100 100 100 100 100100 100 resin Heat-expandable pH 1.5 2.5 3.5 4.0 0.5 1.0 4.5 7.0graphite part 6 6 6 6 6 6 6 6 Lead stearate part 2 2 2 2 2 2 2 2 Calciumpart 3 3 3 3 3 3 3 3 carbonate Lubricant part 0.5 0.5 0.5 0.5 0.5 0.50.5 0.5 Apparatus ◯ ◯ ◯ ◯ X X ◯ ◯ corrosive evaluation Extrusion

molding stability evaluation Performance Tensile strength MPa 48 48 4848 48 48 48 48 evaluation

Fire-resistance Smoke-generating min 120 140 140 120 120 120 100 90evaluation time ◯

◯ ◯ ◯ Δ Δ

TABLE 5 Example Example Example Example Example Comparative 21 22 23 2425 Example 10 Blend Vinyl chloride part 100 100 100 100 100 100component resin Heat-expandable pH 2.5 2.5 2.5 2.5 2.5 2.5 graphite part1 2.5 4 8 10 0 Lead stearate part 2 2 2 2 2 2 Calcium part 3 3 3 3 3 3carbonate Lubricant part 0.5 0.5 0.5 0.5 0.5 0.5 Apparatus ◯ ◯ ◯ ◯ ◯ ◯corrosive evaluation Extrusion

molding stability evaluation Performance Tensile strength MPa 49 49 4847 46 53 evaluation

Fire-resistance Smoke-generating min 120 120 140 140 120 51 evaluationtime ◯ ◯

◯ X Comparative Comparative Comparative Comparative Comparative Example11 Example 12 Example 13 Example 14 Example 15 Blend Vinyl chloride part100 100 100 100 100 component resin Heat-expandable pH 2.5 2.5 2.5graphite part 0.5 12 15 Lead stearate part 2 2 2 2 Calcium part 3 3 3 3carbonate Lubricant part 0.5 0.5 0.5 0.5 0.5 Apparatus ◯ ◯ ◯ ◯ —corrosive evaluation Extrusion

X molding stability evaluation Performance Tensile strength MPa 51 43 4053 — evaluation

◯ ◯

Fire-resistance Smoke-generating min 60 90 42 55 — evaluation time X Δ XX

TABLE 6 Example 26 Example 27 Example 28 Example 29 Example 30 Example31 Blend component Vinyl chloride resin part 100 100 100 100 100 100Heat-expandable pH 2.5 2.5 2.5 2.5 2.5 2.5 graphite part 6 6 6 6 6 6Lead stearate part 0.3 0.5 3 3.5 5 6 Calcium carbonate part 3 3 3 3 3 3Lubricant part 0.5 0.5 0.5 0.5 0.5 0.5 Apparatus corrosive ◯ ◯ ◯ ◯ ◯ ◯evaluation Extrusion molding

stability evaluation Performance Tensile strength MPa 48 48 47 47 46 44evaluation

◯ Fire-resistance Smoke-generating min 140 140 140 140 120 120evaluation time

◯ ◯

TABLE 7 Example 18 Example 32 Example 33 Example 34 Blend componentVinyl chloride resin part 100 100 100 100 Heat-expandable graphite pH2.5 2.5 2.5 2.5 part 6 6 6 6 Lead stearate part 2 Octyltin mercapto part2 Ca/Zn-based composite stabilizer part 3 Epoxidized soybean oil part 3Calcium carbonate part 3 3 3 3 Lubricant part 0.5 0.5 0.5 0.5 Apparatuscorrosive evaluation ◯ ◯ ◯ ◯ Extrusion molding stability

X evaluation Performance evaluation Tensile strength MPa 48 46 47 43

◯ Fire-resistance evaluation Smoke-generating time min 140 140 140 120

◯

TABLE 8 Example 35 Example 36 Example 37 Example 18 Example 38 Example39 Blend component Vinyl chloride resin part 100 100 100 100 100 100Heat-expandable pH 2.5 2.5 2.5 2.5 2.5 2.5 graphite part 6 6 6 6 6 6Lead stearate part 2 2 2 2 2 2 Calcium carbonate part 0 0.3 0.5 3.0 5 8Lubricant part 0.5 0.5 0.5 0.5 0.5 0.5 Apparatus corrosive ◯ ◯ ◯ ◯ ◯ ◯evaluation Extrusion molding ◯

stability evaluation Performance Tensile strength MPa 49 49 49 48 47 45evaluation

Fire-resistance Smoke-generating min 140 140 140 140 120 120 evaluationtime

◯ ◯

TABLE 9 Example 2 Example 40 Example 41 Blend component Vinyl chlorideresin part 100 100 100 Heat-expandable pH 2.5 2.5 2.5 graphite part 6 66 Lead stearate part 2 2 Calcium carbonate part 3 Magnesium hydroxidepart 3 Hydrotalcite part 3 Lubricant part 0.5 0.5 0.5 Apparatuscorrosive ◯ ◯ ◯ evaluation Extrusion molding

X stability evaluation Performance evaluation Tensile strength MPa 48 4848

Fire-resistance Smoke-generating time min 140 120 120 evaluation

◯ ◯

Experimental Results

As shown in Table 4, in Comparative Examples 6 and 7, since the acidityof heat-expandable graphite was too strong, corrosion was observed inthe apparatus. In Comparative Examples 8 and 9, the acidity ofheat-expandable graphite was too weak, and therefore the carbonizationof the vinyl chloride resin during burning was hardly accelerated,resulting in that a smoke-generating time of 120 minutes was notachieved in the fire-resistance evaluation.

It was confirmed from these results that in order to exhibit excellentfire resistance without causing corrosion of apparatus, the pH ofheat-expandable graphite is required to be in the range of 1.5 to 4.0.

As shown in Table 5, in Comparative Examples 10 and 11, since theblending ratio of heat-expandable graphite was too small, asmoke-generating time of 120 minutes was not achieved in thefire-resistance evaluation. On the other hand, in Comparative Examples12 and 13, since the blending ratio of heat-expandable graphite was toolarge, a smoke-generating time of 120 minutes was not achieved in thefire-resistance evaluation.

It was confirmed from these results that in order to obtain excellentfire resistance while strength necessary as a pipe is maintained, theheat-expandable graphite is required to have a pH of 1.5 to 4.0 and iscontained in an amount of 1 to 10 parts by weight based on 100 parts byweight of the vinyl chloride resin. Furthermore, when the amount of theheat-expandable graphite was larger than 10 parts by weight, the heatedcomposition was thermally expanded too much to maintain the shape,resulting in dropping of the residue 2, as shown in FIG. 8.

As shown in Table 6, in Example 31, since the additive amount of thestabilizer is too large, the tensile strength was lower than those inExamples 26 to 30.

As shown in Table 7, in Example 34, epoxidized soybean oil was blendedas an additive for providing heat stability during molding. Epoxidizedsoybean oil does not have high ability of providing heat stabilityduring molding, but has high effect of plasticization. As a result, thesample of Example 34 was rejected in the extrusion molding stability andwas also slightly reduced in tensile strength and fire resistance,compared to those in other Examples shown in Table 7.

It was confirmed from these results that in order to obtain a pipe thatis excellent in tensile strength and fire resistance and also excellentin molding stability, it is preferred that at least one selected fromthe group consisting of lead-based stabilizers, organic tin-basedstabilizers, and higher fatty acid metal salts be contained as theadditive for providing heat stability during molding in a total additiveamount of 0.3 to 5.0 parts by weight based on 100 parts by weight of thepolyvinyl chloride-based resin.

As shown in Table 8, in Example 35, since calcium carbonate serving as abasic compound was not contained, the extrusion molding stability wasslightly lower than those in other Examples shown in Table 8. On theother hand, in Example 39, the additive amount of calcium carbonateserving as a basic compound was too large, and thereby the tensilestrength was slightly lower than those in other Examples shown in Table8.

As shown in Table 9, in Example 41, no stabilizer was blended as theadditive for providing heat stability during molding, and onlyhydrotalcite was blended. Though hydrotalcite has an ability ofproviding heat stability, sufficient heat stability cannot be achievedby hydrotalcite alone. Consequently, the sample was rejected in theextrusion molding stability.

It was confirmed from these results that in order to obtain a pipe thatis excellent in tensile strength and fire resistance and also excellentin molding stability, it is further preferred that each of a stabilizeras the additive for providing heat stability during molding and a basiccompound be contained in an amount of 0.3 to 5.0 parts by weight basedon 100 parts by weight of the vinyl chloride resin.

TABLE 10 Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- pleple ple ple ple ple ple ple ple ple 42 43 44 45 46 47 48 49 50 51 Blendcomponent Vinyl chloride resin part 100 100 100 100 100 100 100 100 100100 Heat-expandable part 1 3 6 8 10 6 6 6 6 8 graphite Organic tin-basedpart 1 1 1 1 1 1 1 1 1 1 stabilizer Lubricant part 0.5 0.5 0.5 0.5 0.50.5 0.5 0.5 0.5 0.5 Stearic acid part 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.50.5 0.5 Expansion volume of heat-expandable mL/g 200 200 200 200 200 250190 180 100 150 graphite Heat expansibility Thickness after mm 4 7 10 1213 12 9 10 5 12 evaluation expansion ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ PerformanceTensile strength MPa 52 51 48 47 45 48 48 48 48 47 evaluation

Fire-resistance Smoke-generating min 120 120 120 120 120 120 120 120 120120 evaluation time ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Pipe inner cross- % 50 45 40 2520 35 40 40 47 40 sectional area ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ proportion

TABLE 11 Exam- Exam- Exam- Exam- Exam- Exam- ple ple ple ple ple pleComparative Comparative Comparative 52 53 54 55 56 57 Example 16 Example17 Example 18 Blend Vinyl chloride part 100 100 100 100 100 100 100 100100 component resin Heat- part 1 3 6 10 6 6 0 15 6 expandable graphiteCalcium part 6 10 15 carbonate Organic tin- part 1 1 1 1 1 1 1 1 basedstabilizer Lubricant part 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Stearic acidpart 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Expansion volume of heat- mL/g 180180 180 180 180 180 200 180 expandable graphite Heat Thickness after mm4 7 10 13 12 12 0 0 12 expansibility expansion ◯ ◯ ◯ ◯ ◯ ◯ X X broken ◯evaluation Performance Tensile MPa 52 51 48 45 46 45 53 41 43 evaluationstrength

◯ ◯ Fire- Smoke- min 120 120 120 120 120 120 50 55 120 resistancegenerating time ◯ ◯ ◯ ◯ ◯ ◯ X X ◯ evaluation Pipe inner % 50 45 40 20 4035 bumed-out dropped 55 cross- ◯ ◯ ◯ ◯ ◯ ◯ X X X sectional areaproportion

TABLE 12 Example Example Example Example Example Example Example Example58 59 60 61 62 63 64 65 Blend component Vinyl chloride resin part 100100 100 100 100 100 100 100 Heat-expandable graphite part 1 4 7 10 5 5 55 Calcium carbonate part 3 3 3 3 0 1 5 7 Lead-based stabilizer part 2 22 2 2 2 2 2 Lubricant part 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Heatexpansibility Thickness after mm 4 8 11 13 8 8 9 10 evaluation expansion◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Performance Tensile strength MPa 51 49 46 45 49 49 47 47evaluation

Fire-resistance Smoke-generating time min 120 140 140 120 120 140 140120 evaluation ◯

◯ ◯

◯ Pipe inner cross-sectional % 50 5 5 20 35 10 10 35 area proportion ◯

◯ ◯

◯ Elongated length mm 30 120 80 40 40 100 90 20 ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯

TABLE 13 Example Example Example Example Example Comparative Comparative66 67 68 69 70 Example 19 Example 20 Blend component Vinyl chlorideresin part 100 100 100 100 100 100 100 Heat-expandable part 5 5 5 5 5 015 graphite Calcium carbonate part 3 3 3 3 0 3 3 Lead-based stabilizerpart 0.1 0.3 3 5 7 2 2 Lubricant part 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Heatexpansibility Thickness after mm 9 9 9 9 8 0 0 evaluation expansion ◯ ◯◯ ◯ ◯ X X Performance Tensile strength MPa 48 48 48 48 49 52 40evaluation

◯ Molding property evaluation Δ ◯ ◯ ◯ ◯ ◯ ◯ slight drift Fire-resistanceSmoke-generating time min 120 140 140 140 120 50 55 evaluation ◯

◯ X X Pipe inner cross- % 20 10 5 10 45 burned-out dropped sectional ◯

◯ X X area proportion Elongated length mm 30 100 100 80 30 0 10 ◯ ◯ ◯ ◯◯ X X

Experimental Results

As shown in Tables 11 and 13, in Comparative Examples 16 and 19, sinceheat-expandable graphite was not blended at all, the piping materialburned out. As a result, the increase in temperature of the pipingmaterial was rapid on the heating side, and thereby the smoke-generatingtime was short.

In Comparative Examples 17 and 20, since the blended amount of theheat-expandable graphite was too large, the piping material could notmaintain the shape thereof after expansion, and dropped. As a result,the temperature of the piping material was rapidly increased on theheating side, and thereby the smoke-generating time was short.

Furthermore, when the amount of the heat-expandable graphite was largerthan 10 parts by weight, the heated composition was thermally expandedtoo much to maintain the shape, resulted in dropping of the residue, asshown in FIG. 8.

Therefore, it was well confirmed that in order to obtain asingle-layered fire-resistant piping material that satisfies all theheat expansibility evaluation, performance evaluation, andfire-resistance evaluation requirements, the heat-expandable graphite isrequired to have an expansion volume of 100 to 250 mL/g and to becontained in the range of 1 to 10 parts by weight based on 100 parts byweight of the vinyl chloride resin.

Furthermore, in Examples 42 to 70, not only the tensile strengthnecessary as a pipe was achieved, but also the smoke-generating time wasdrastically elongated, compared to those in Comparative Examples. Thismay be caused by that in Examples 42 to 70, the pipe inner cross-sectionwas caulked with the residue to inhibit an increase in temperature ofthe pipe.

Furthermore, in Examples 59 and 60, not only the pipe innercross-sectional area proportion but also the elongated length L of theresidue H was excellent, compared to those in Examples 58 and 61. InExamples 63 and 64, not only the pipe inner cross-sectional areaproportion but also the elongated length L of the residue H wasexcellent, compared to those in Examples 62 and 65. In addition, inExamples 67 to 69, not only the pipe inner cross-sectional areaproportion but also the elongated length L of the residue H wasexcellent, compared to those in Examples 66 and 70. As a result, inthese Examples, the smoke-generating time was further improved comparedto other Examples.

Incidentally, when a synthetic resin piping material constructed so asto pass through a floor material is heated from the underside of thefloor, first, the portion of the piping material protruding below thefloor is directly heated to start softening and burning. Then, adifference in hardness occurs between the portion lying inside thecomposition and the burning portion of the floor piping material,causing sharp softening. Then, the portion of the piping materialprotruding below the floor falls apart from the floor and drops (fallsaway) about 5 to 20 minutes after the start of the burning. The bottomsurface of the remaining piping material is in nearly the same plane asthe bottom surface of the floor. When the heat is further applied, thephenomena vary depending on the blending composition of the pipingmaterial.

Specifically, in the piping material composed of the composition shownin Comparative Example 19, as shown in FIG. 9, after the portionprotruding below the floor dropped, the resin run down to once caulk theend on the heating side. However, since no heat-expandable graphite wasblended, fire resistance was not obtained, and the end of the pipingmaterial on the heating side dropped after all. As a result, hot airflowed in the inside of the pass-through portion of the piping material,and the potion inside the floor structure burned out to generate smokeon the non-heating side.

Since the piping material composed of the composition shown inComparative Example 20 contained a large amount of heat-expandablegraphite, the heated composition was expanded too much to maintain theshape, resulting in dropping.

On the other hand, in the piping materials composed of compositionsshown in Examples 66 to 70, as shown in FIG. 10, after the portionprotruding below the floor dropped, the remaining portion was softenedfrom the lower part by being heated, and the inner diameter slightlyshrank in the direction in which the pipe contracts. Then, theheat-expandable graphite started expanding by heating. The expansioncontinued in the central direction of the pipe cross-section till thatthe pipe inner cross-sectional area after burning became 50% or less ofthe pipe inner cross-sectional area before the burning. The residueafter the expansion was thought that the main component thereof was agraphite crystal, which gives a very strong, flame-retardant residue Hextending from the underside of the floor to the heating side and canprevent itself from dropping and burning. As a result, even though theunderside of the floor was heated to 1000° C. or higher, the residue Hdid not drop from the underside of the floor, and a state of almostcaulking the pipe continued for a long period of time. In addition,since the pipe inner cross-sectional area was reduced during burning andalso the residue extended to the heating side, hot air was preventedfrom ascending inside the pipe and an increase in temperature of thepiping material on the non-heating side with respect to the floorsurface could be suppressed. As a result, the piping material wasprevented from burning out, and also smoke generation on the non-heatingside, which is caused by softening of the piping material to form a gapwith the mortar interface, was prevented.

Therefore, it was confirmed that in order to obtain a single-layeredfire-resistant piping material that satisfies all the strength as apipe, stability during molding, and caulking of the end on the heatingside of the pipe during heating, it is necessary that heat-expandablegraphite having an expansion volume in the range of 100 to 250 mL/g iscontained in an amount of 1 to 10 parts by weight based on 100 parts byweight of the vinyl chloride resin.

Furthermore, it was confirmed that further preferred blending ratiosare, based on 100 parts by weight of the vinyl chloride resin, 4 to 7parts by weight of the heat-expandable graphite having an expansionvolume in the range of 100 to 250 mL/g, 1 to 5 parts by weight ofcalcium carbonate serving as the inorganic filler, and 0.3 to 5 parts byweight of the stabilizer.

TABLE 14 Example Example Example Example Example Comparative Comparative71 72 73 74 75 Example 21 Example 22 Blend component Vinyl chlorideresin part 100 100 100 100 100 100 100 Heat-expandable part 1 10 5 5 5 012 graphite Lead-based part 2 2 2 2 2 2 2 stabilizer Lubricant part 0.50.5 0.5 0.5 0.5 0.5 0.5 1.3-time expansion temperature ° C. 200 200 180240 200 — 200 Resin temperature during molding ° C. 180 180 170 210 195180 180 Fire-resistance Smoke-generating min 120 120 120 120 120 55 90evaluation time ◯ ◯ ◯ ◯ ◯ X Δ Performance Tensile strength MPa 52 45 4949 49 53 43 evaluation

◯ Molding property ◯ ◯ ◯ ◯ ◯ ◯ ◯ evaluation

Experimental Results

It was confirmed that in order to provide strength necessary as a pipeand to exhibit excellent fire resistance, it is necessary that theheat-expandable graphite having a 1.3-time expansion temperature T3 of180 to 240° C. is contained in an amount of 1 to 10 parts by weightbased on 100 parts by weight of the vinyl chloride resin.

When the amount of the heat-expandable graphite was larger than 10 partsby weight, the heated composition was thermally expanded too much tomaintain the shape, resulting in dropping of the residue 2, as shown inFIG. 8.

TABLE 15 Example Example Example Example Example Comparative ComparativeBlend component 76 77 78 79 80 Example 23 Example 24 Inner side Vinylchloride resin part — — — — — — — covering layer Lead-based stabilizerpart — — — — — — — Lubricant part — — — — — — — Calcium carbonate part —— — — — — — Fire-resistant Vinyl chloride resin part 100 100 100 100 100100 100 expandable Lead-based stabilizer part 2 2 2 2 2 2 2 layerLubricant part 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Calcium carbonate part 3 3 33 3 3 3 Heat-expandable graphite part 1 2 7 14 15 0 17 Outer side Vinylchloride resin part 100 100 100 100 100 100 100 covering layerLead-based stabilizer part 2 2 2 2 2 2 2 Lubricant part 0.5 0.5 0.5 0.50.5 0.5 0.5 Calcium carbonate part 3 3 3 3 3 3 3 Layer Inner sidecovering layer mm — — — — — — — thickness Fire-resistant mm 5.61 5.615.61 5.61 5.61 5.61 5.61 (thickness expandable layer (85%) (85%) (85%)(85%) (85%) (85%) (85%) proportion %) Outer side covering layer mm 0.990.99 0.99 0.99 0.99 0.99 0.99 (15%) (15%) (15%) (15%) (15%) (15%) (15%)Fire-resistance Smoke-generating time min ◯ ◯

◯ ◯ X X evaluation 120 120 131 127 120 55 45 Performance Tensilestrength MPa

◯ ◯

◯ evaluation 51.4 50.7 47.3 42.6 41.9 52.1 40.5

TABLE 16 Example Example Example Example Example Comparative ComparativeBlend component 81 82 83 84 85 Example 25 Example 26 Inner side Vinylchloride resin part 100 100 100 100 100 100 100 covering layerLead-based stabilizer part 2 2 2 2 2 2 2 Lubricant part 0.5 0.5 0.5 0.50.5 0.5 0.5 Calcium carbonate part 3 3 3 3 3 3 3 Fire-resistant Vinylchloride resin part 100 100 100 100 100 100 100 expandable Lead-basedstabilizer part 2 2 2 2 2 2 2 layer Lubricant part 0.5 0.5 0.5 0.5 0.50.5 0.5 Calcium carbonate part 3 3 3 3 3 3 3 Heat-expandable graphitepart 1 2 7 14 15 0 17 Outer side Vinyl chloride resin part — — — — — — —covering layer Lead-based stabilizer part — — — — — — — Lubricant part —— — — — — — Calcium carbonate part — — — — — — — Layer Inner sidecovering layer mm 0.99 0.99 0.99 0.99 0.99 0.99 0.99 thickness (15%)(15%) (15%) (15%) (15%) (15%) (15%) (thickness Fire-resistant expandablemm 5.61 5.61 5.61 5.61 5.61 5.61 5.61 proportion %) layer (85%) (85%)(85%) (85%) (85%) (85%) (85%) Outer side covering layer mm — — — — — — —Fire-resistance Smoke-generating time min ◯ ◯

◯ ◯ X X evaluation 120 120 130 126 120 57 48 Performance Tensilestrength MPa

◯ ◯

◯ evaluation 51.2 50.8 47.5 42.5 41.7 51.9 40.4

TABLE 17 Example Example Example Example Example Comparative ComparativeBlend component 86 87 88 89 90 Example 27 Example 28 Inner side Vinylchloride resin part 100 100 100 100 100 100 100 covering layerLead-based stabilizer part 2 2 2 2 2 2 2 Lubricant part 0.5 0.5 0.5 0.50.5 0.5 0.5 Calcium carbonate part 3 3 3 3 3 3 3 Fire-resistant Vinylchloride resin part 100 100 100 100 100 100 100 expandable Lead-basedstabilizer part 2 2 2 2 2 2 2 layer Lubricant part 0.5 0.5 0.5 0.5 0.50.5 0.5 Calcium carbonate part 3 3 3 3 3 3 3 Heat-expandable graphitepart 1 2 7 14 15 0 17 Outer side Vinyl chloride resin part 100 100 100100 100 100 100 covering layer Lead-based stabilizer part 2 2 2 2 2 2 2Lubricant part 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Calcium carbonate part 3 3 33 3 3 3 Layer Inner side covering layer mm 0.66 0.66 0.66 0.66 0.66 0.660.66 thickness (10%) (10%) (10%) (10%) (10%) (10%) (10%) (thicknessFire-resistant expandable mm 5.28 5.28 5.28 5.28 5.28 5.28 5.28proportion %) layer (80%) (80%) (80%) (80%) (80%) (80%) (80%) Outer sidecovering layer mm 0.66 0.66 0.66 0.66 0.66 0.66 0.66 (10%) (10%) (10%)(10%) (10%) (10%) (10%) Fire-resistance Smoke-generating time min ◯ ◯

◯ ◯ X X evaluation 120 120 130 125 120 54 44 Performance Tensilestrength MPa

◯ ◯

◯ evaluation 51.5 50.9 47.7 43.2 42.6 52.2 41.3

TABLE 18 Example Example Example Example Example Example Example ExampleBlend component 91 92 93 94 95 96 97 98 Inner side Vinyl chloride resinpart 100 100 100 100 100 100 100 100 covering layer Lead-basedstabilizer part 2 2 2 2 2 2 2 2 Lubricant part 0.5 0.5 0.5 0.5 0.5 0.50.5 0.5 Calcium carbonate part 3 3 3 3 3 3 3 3 Fire-resistant Vinylchloride resin part 100 100 100 100 100 100 100 100 expandableLead-based stabilizer part 2 2 2 2 2 2 2 2 layer Lubricant part 0.5 0.50.5 0.5 0.5 0.5 0.5 0.5 Calcium carbonate part 40 40 40 40 40 40 40 40Heat-expandable graphite part 5 5 5 5 5 5 5 5 Ammonium polyphosphatepart 0 0 0 0 0 0 0 0 Outer side Vinyl chloride resin part — — — — — 100100 100 covering layer Lead-based stabilizer part — — — — — 2 2 2Lubricant part — — — — — 0.5 0.5 0.5 Calcium carbonate part — — — — — 33 3 Layer Inner side covering layer mm 5.94 4.62 3.3 1.98 0.66 0.66 1.52.64 thickness (90%) (70%) (50%) (30%) (10%) (10%) (23%) (40%)(thickness Fire-resistant expandable mm 0.66 1.98 3.3 4.62 5.94 5.28 3.61.32 proportion %) layer (10%) (30%) (50%) (70%) (90%) (80%) (54%) (20%)Outer side covering layer mm — — — — — 0.66 1.5 2.64 (10%) (23%) (40%)Fire-resistance Smoke-generating time min ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ evaluation 120120 120 120 120 120 120 120 Performance Tensile strength MPa

evaluation 50.0 49.1 48.2 47.2 46.3 46.7 48.0 49.6

TABLE 19 Comparative Comparative Blend component Example 29 Example 30Inner side Vinyl chloride resin part — 100 covering layer Lead-basedpart — 2 stabilizer Lubricant part — 0.5 Calcium carbonate part — 3Fire-resistant Vinyl chloride resin part 100 — expandable Lead-basedpart 2 — layer stabilizer Lubricant part 0.5 — Calcium carbonate part100 — Heat-expandable part 30 — graphite Ammonium part 100 —polyphosphate Outer side Vinyl chloride resin part — — covering layerLead-based part — — stabilizer Lubricant part — — Calcium carbonate part— — Layer Inner side covering mm — 6.6 thickness layer (100%) (thicknessFire-resistant mm 6.6 — proportion %) expandable (100%) layer Outer sidecovering mm — — layer Fire-resistance Smoke-generating min ◯ Xevaluation time 120 55 flame burst Performance Tensile strength MPa ◯ ⊚evaluation 33.4 50.5

Experimental Results

As shown in Tables 15 to 19, in Comparative Examples 23 to 28 and 30,the smoke-generating time was short, and the samples were rejected inthe fire-resistance evaluation. In addition, in Comparative Example 29,the tensile strength was slightly low. Therefore, in order to obtain amultilayered fire-resistant piping material that satisfies both thefire-resistance evaluation and performance evaluation requirements, itis necessary, as shown in Examples 76 to 90, that the material include atubular fire-resistant expandable layer composed of a heat-expandablefire-resistant resin composition and a covering layer covering at leastone of the outer surface and the inner surface of the fire-resistantexpandable layer, the fire-resistant expandable layer is formed of afire-resistant resin composition containing heat-expandable graphite inan amount of 1 to 15 parts by weight based on 100 parts by weight of thevinyl chloride resin, and the covering layer is formed of a vinylchloride resin composition not containing heat-expandable fire-resistantmaterials.

When the amount of the heat-expandable graphite was larger than 15 partsby weight, the heated test piping material P was thermally expanded toomuch to maintain the shape, resulting in dropping of the residue, asshown in FIG. 8.

TABLE 20 Exam- Exam- Exam- ple ple ple Example Example Example ExampleExample Comparative Blend component 99 100 101 102 103 104 105 106Example 31 Inner side Vinyl chloride resin part 100 100 100 100 100 100100 100 100 covering layer Lead-based stabilizer part 2 2 2 2 2 2 2 2 2Lubricant part 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Calcium carbonatepart 3 3 3 3 3 3 3 3 3 Fire-resistant Vinyl chloride resin part 100 100100 100 100 100 100 100 100 expandable Lead-based stabilizer part 2 2 22 2 2 2 2 2 layer Lubricant part 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5Calcium carbonate part 3 3 3 3 3 3 3 3 3 Heat-expandable part 5 10 15 1010 10 10 10 17 graphite 1.3-time expansion ° C. 210 210 210 170 180 190240 250 210 temperature Outer side Vinyl chloride resin part 100 100 100100 100 100 100 100 100 covering layer Lead-based stabilizer part 2 2 22 2 2 2 2 2 Lubricant part 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Calciumcarbonate part 3 3 3 3 3 3 3 3 3 Layer Inner side covering mm 0.66 0.660.66 0.66 0.66 0.66 0.66 0.66 0.66 thickness layer (10%) (10%) (10%)(10%) (10%) (10%) (10%) (10%) (10%) (thickness Fire-resistant mm 5.285.28 5.28 5.28 5.28 5.28 5.28 5.28 5.28 proportion %) expandable layer(80%) (80%) (80%) (80%) (80%) (80%) (80%) (80%) (80%) Outer sidecovering mm 0.66 0.66 0.66 0.66 0.66 0.66 0.66 0.66 0.66 layer (10%)(10%) (10%) (10%) (10%) (10%) (10%) (10%) (10%) Fire-resistanceSmoke-generating time min ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ X evaluation 125 127 123 120122 125 123 120 58 Performance Tensile strength MPa

◯

◯ ◯ evaluation 49.0 45.8 42.6 45.2 45.4 45.7 45.9 44.5 41.3

Experimental Results

As shown in Table 20, in Comparative Example 31, the smoke-generatingtime was very short, compared to those in Examples 99 to 101, and thesample was rejected in the fire-resistance evaluation.

In Examples 102 and 106, the smoke-generating time was slightly short,and the samples were slightly inferior in the fire-resistanceevaluation, compared to those in Examples 100, 103, 104, and 105.

Therefore, it was confirmed that in order to satisfy both thefire-resistance evaluation and performance evaluation requirements, itis preferable that the fire-resistant expandable layer 11 is formed of afire-resistant resin composition containing heat-expandable graphitehaving a 1.3-time expansion temperature in the range of 180 to 240° C.in an amount of 5 to 15 parts by weight based on 100 parts by weight ofthe polyvinyl chloride-based resin.

TABLE 21 Example Example Example Example Example Example Example Blendcomponent 107 108 109 110 111 112 113 Inner side Vinyl chloride resinpart 100 100 100 100 100 100 100 covering layer Lead-based stabilizerpart 2 2 2 2 2 2 2 Lubricant part 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Calciumcarbonate part 3 3 3 3 3 3 3 Fire-resistant Vinyl chloride resin part100 100 100 100 100 100 100 expandable Lead-based stabilizer part 2 2 22 2 2 2 layer Lubricant part 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Calciumcarbonate part 3 3 3 3 3 3 3 Heat-expandable graphite part 10 10 10 1010 10 10 1.3-time expansion ° C. 210 210 210 210 210 210 210 temperatureOuter side Vinyl chloride resin part 100 100 100 100 100 100 100covering layer Lead-based stabilizer part 2 2 2 2 2 2 2 Lubricant part0.5 0.5 0.5 0.5 0.5 0.5 0.5 Calcium carbonate part 3 3 3 3 3 3 3 Layerthickness Inner side covering layer mm 0.2 0.5 1.0 1.5 2.0 0.1 2.2(thickness (3%) (8%) (15%) (23%) (30%) (2%) (33%) proportion %)Fire-resistant expandable layer mm 6.2 5.6 4.6 3.6 2.6 6.4 2.2 (94%) (85%)  (70%) (55%) (40%) (97%)  (33%) Outer side covering layer mm 0.20.5 1.0 1.5 2.0 0.1 2.2 (3%) (8%) (15%) (23%) (30%) (2%) (33%)Fire-resistance Smoke-generating time min

◯ ◯ ◯ ◯

◯ evaluation 130 128 125 123 122 132 120 Performance Tensile strengthMPa ◯

◯

evaluation 43.4 45.8 46.7 48.6 49.4 39.8 49.5

Experimental Results

As shown in Table 21, in Example 112, since the thicknesses of the innerside covering layer 12 and the outer side covering layer 13 were eachextremely thin, 0.1 mm, the tensile strength was slightly inferior,compared to those in other Examples. On the other hand, in Example 113,since the thicknesses of the inner side covering layer 12 and the outerside covering layer 13 were each extremely thick, 2.2 mm, the fireresistance was slightly inferior, compared to those in other Examples.

Therefore, it was confirmed that it is preferable that the thicknessesof the inner side covering layer 12 and the outer side covering layer 13each be in the range of 0.2 to 2.0 mm.

TABLE 22 Comparative Comparative Blend component Example 114 Example 115Example 116 Example 32 Example 33 Inner side Vinyl chloride resin part100 100 100 100 100 covering layer Lead-based stabilizer part 2 2 2 2 2Lubricant part 0.5 0.5 0.5 0.5 0.5 Calcium carbonate part 3 3 3 3 3Fire-resistant Vinyl chloride resin part 100 100 100 100 100 expandableLead-based stabilizer part 2 2 2 2 2 layer Lubricant part 0.5 0.5 0.50.5 0.5 Calcium carbonate part 3 3 3 3 3 Heat-expandable graphite part10 10 10 10 10 1.3-time expansion ° C. 230 230 230 230 230 temperatureOuter side Vinyl chloride resin part 100 100 100 100 100 covering layerLead-based stabilizer part 2 2 2 2 2 Lubricant part 0.5 0.5 0.5 0.5 0.5Calcium carbonate part 3 3 3 3 3 Layer Inner side covering layer mm 1.01.0 1.0 1.0 1.0 thickness (15%) (15%) (15%) (15%) (15%) (thicknessFire-resistant expandable mm 4.6 4.6 4.6 4.6 4.6 proportion %) layer(70%) (70%) (70%) (70%) (70%) Outer side covering layer mm 1.0 1.0 1.01.0 1.0 (15%) (15%) (15%) (15%) (15%) Resin temperature during molding °C. 170 190 210 160 220 Fire- Smoke-generating time min ◯ ◯ ◯ ◯ ◯resistance 125 126 125 120 120 evaluation Performance Tensile strengthMPa

◯ ◯ evaluation 45.3 46.7 46.9 35.6 38.9

Experimental Results

As shown in Table 22, in Comparative Example 32, since the resintemperature during molding was too low, the tensile strength wasslightly inferior. Furthermore, in Comparative Example 33, since theresin temperature during molding was too high, the tensile strength wasslightly inferior. Therefore, it is preferable that the resintemperature during molding of the resin composition be 170 to 210° C.

TABLE 23 Blend component Example 117 Example 118 Example 119 Example 120Comparative Example 34 Inner side Vinyl chloride resin part 100 100 100100 100 covering layer Lead-based stabilizer part 2 2 2 2 2 Lubricantpart 0.5 0.5 0.5 0.5 0.5 Calcium carbonate part 3 3 3 3 3 Fire-resistantVinyl chloride resin part 100 100 100 100 100 expandable Lead-basedstabilizer part 2 2 2 2 2 layer Lubricant part 0.5 0.5 0.5 0.5 0.5Calcium carbonate part 3 3 3 3 3 Heat-expandable graphite part 10 10 1010 10 1.3-time expansion ° C. 180 200 240 250 160 temperature Outer sideVinyl chloride resin part 100 100 100 100 100 covering layer Lead-basedstabilizer part 2 2 2 2 2 Lubricant part 0.5 0.5 0.5 0.5 0.5 Calciumcarbonate part 3 3 3 3 3 Layer Inner side covering layer mm 1.0 1.0 1.01.0 1.0 thickness (15%) (15%) (15%) (15%) (15%) (thicknessFire-resistant expandable mm 4.6 4.6 4.6 4.6 4.6 proportion %) layer(70%) (70%) (70%) (70%) (70%) Outer side covering layer mm 1.0 1.0 1.01.0 1.0 (15%) (15%) (15%) (15%) (15%) Resin temperature during molding °C. 170 195 210 180 170 Fire-resistance Smoke-generating time min ◯ ◯ ◯ ◯◯ evaluation 129 123 125 120 120 Performance Tensile strength MPa

◯ ◯ evaluation 46.5 46.7 46.8 40.2 36.6

Experimental Results

As shown in Table 23, in Comparative Example 23, since the 1.3-timeexpansion temperature of the heat-expandable graphite was lower than theresin temperature during molding by 10° C., the tensile strength waslower than those in Examples 117 to 120. Furthermore, in Example 120,since the 1.3-time expansion temperature of the heat-expandable graphitewas higher than 240° C., the smoke-generating time was slightly short,and the tensile strength was slightly inferior, compared to those inExamples 117 to 119.

Therefore, it was confirmed that it is preferable that the resintemperature during molding be lower than the 1.3-time expansiontemperature of heat-expandable graphite by 5° C. and be in 170 to 210°C.

CONCLUSION

As described in detail with reference to Examples in the above, in thesingle-layered fire-resistant piping material and the multilayeredfire-resistant piping material according to the present invention, eachlayer constituted of a fire-resistant resin composition effectivelyexpands during burning, and, as shown in FIG. 11, the residue caulks thegap between the piping material and the compartment pass-through portionand the inside of the piping material to prevent flame and smoke frompenetrating to the other side partitioned by the floor material. Thepiping materials are thus excellent in fire resistance and alsoexcellent in molding properties and have mechanical strength sufficientas pipes.

Furthermore, unlike a piping structure in which only the compartmentpass-through portion is subjected to fire-resistant treatment with aconventional fire-resistant expandable sheet-like covering material, thepresent invention can impart fire resistance to the entire piping.

In the present fire-resistance evaluation, the fire resistance wascompared by an alternative evaluation technique in which heating isconducted under a condition that one end of a piping material protrudesin a fire-resistant furnace by 300 mm. In the case of a fire under acondition that the piping material of the present invention ispractically constructed in a building so as to pass through each slab ofevery floor or each partition wall of every floor, the difference infire resistance may be further distinguished.

That is, the piping material of the present invention rapidly andreliably caulks the compartment pass-through portion during burning, andalso the entire pipe can undergo burning for a long period of time. Evenif the piping material partially dropped during burning, it is suggestedthat the opening portion of the piping material is quickly caulked tomaintain the shape, and thereby flame and smoke hardly penetrate to theoutside of the burning chamber, resulting in prevention of the fire fromspreading.

Furthermore, in the multilayered fire-resistant piping material havingan inner side covering layer, the inner circumference surface of thepiping material is smooth and thereby can allow fluid to smoothly pass,and also the inner circumference surface of the piping material isexcellent in chemical proof and thereby hardly limits the type of fluid,which allows general purpose application.

In addition, in the multilayered fire-resistant piping material havingan outer side covering layer, the outer circumference surface of thepiping material is excellent in adhesion and, for example, can be easilyand reliably connected to another member such as a pipe joint.

Furthermore, the multilayered fire-resistant piping material of thepresent invention is not limited to the above-described Examples. Forexample, in the Examples, the piping materials have a nominal diameterof 100 mm, but may have a nominal diameter different therefrom.

1. A single-layered fire-resistant piping material, comprising a fire-resistant resin composition containing heat-expandable graphite in an amount of 1 to 10 parts by weight based on 100 parts by weight of a polyvinyl chloride-based resin.
 2. A single-layered fire-resistant piping material, comprising a fire-resistant resin composition containing heat-expandable graphite having a pH of 1.5 to 4.0 in an amount of 1 to 10 parts by weight based on 100 parts by weight of a polyvinyl chloride-based resin.
 3. The single-layered fire-resistant piping material according to claim 2, wherein the fire-resistant resin composition contains an additive for providing heat stability during molding.
 4. The single-layered fire-resistant piping material according to claim 3, wherein at least one selected from the group consisting of lead-based stabilizers, organic tin-based stabilizers, and higher fatty acid metal salts is contained as the additive for providing heat stability during molding in a total additive amount of 0.3 to 5.0 parts by weight based on 100 parts by weight of the polyvinyl chloride-based resin.
 5. The single-layered fire-resistant piping material according to claim 4, wherein a basic compound is further contained as the additive for providing heat stability during molding in a total additive amount of 0.3 to 5.0 parts by weight based on 100 parts by weight of the polyvinyl chloride-based resin.
 6. A single-layered fire-resistant piping material, comprising a fire-resistant resin composition containing heat-expandable graphite having an expansion volume in the range of 100 to 250 mL/g in an amount of 1 to 10 parts by weight based on 100 parts by weight of a polyvinyl chloride-based resin.
 7. A single-layered fire-resistant piping material, comprising a fire-resistant resin composition containing heat-expandable graphite having a 1.3-time expansion temperature of 180 to 240° C. in an amount of 1 to 10 parts by weight based on 100 parts by weight of a polyvinyl chloride-based resin.
 8. The single-layered fire-resistant piping material according to any one of claims 1 to 7, wherein when the piping material is constructed so as to pass through a flooring material and is subjected to a fire-resistant test (complying with ISO 834-1) in which the underside of the floor is heated under conditions that one end of the piping material is exposed to a heating side by 300 mm from the surface on the heating side of the flooring material and that the other end of the piping material is exposed to a non-heating side by 800 mm from the surface on the non-heating side of the flooring material, a pipe inner cross-sectional area S1 at the end of the piping material before burning on the heating side and a pipe inner cross-sectional area S2 at a minimum inner diameter of the piping material after burning satisfy a relationship: (S2/S1)×100≦50.
 9. A multilayered fire-resistant piping material, comprising a tubular fire-resistant expandable layer made of a heat-expandable fire-resistant resin composition and a covering layer covering at least one of the outer surface and the inner surface of the fire-resistant expandable layer, wherein the fire-resistant expandable layer is formed of a fire-resistant resin composition containing heat-expandable graphite in an amount of 1 to 15 parts by weight based on 100 parts by weight of a polyvinyl chloride-based resin, and the covering layer is formed of a polyvinyl chloride-based resin composition not containing heat-expandable fire-resistant materials.
 10. A multilayered fire-resistant piping material, comprising a tubular fire-resistant expandable layer made of a heat-expandable fire-resistant resin composition and a covering layer covering at least one of the outer surface and the inner surface of the fire-resistant expandable layer, wherein the fire-resistant expandable layer is formed of a fire-resistant resin composition containing heat-expandable graphite having a pH of 1.5 to 4.0 in an amount of 1 to 15 parts by weight based on 100 parts by weight of a polyvinyl chloride-based resin; and the covering layer is formed of a polyvinyl chloride-based resin composition not containing heat-expandable fire-resistant materials.
 11. The multilayered fire-resistant piping material according to claim 10, wherein the fire-resistant resin composition contains an additive for providing heat stability during molding.
 12. The multilayered fire-resistant piping material according to claim 11, wherein at least one selected from the group consisting of lead-based stabilizers, organic tin-based stabilizers, and higher fatty acid metal salts is contained as the additive for providing heat stability during molding in a total additive amount of 0.3 to 5.0 parts by weight based on 100 parts by weight of the polyvinyl chloride-based resin.
 13. The multilayered fire-resistant piping material according to claim 12, wherein a basic compound is further contained as the additive for providing heat stability during molding in a total additive amount of 0.3 to 5.0 parts by weight based on 100 parts by weight of the polyvinyl chloride-based resin.
 14. A multilayered fire-resistant piping material, comprising a tubular fire-resistant expandable layer made of a heat-expandable fire-resistant resin composition and a covering layer covering at least one of the outer surface and the inner surface of the fire-resistant expandable layer, wherein the fire-resistant expandable layer is constituted of a fire-resistant resin composition containing heat-expandable graphite having an expansion volume in the range of 100 to 250 mL/g in an amount of 1 to 15 parts by weight based on 100 parts by weight of a polyvinyl chloride-based resin; and the covering layer is constituted of a polyvinyl chloride-based resin composition not containing heat-expandable fire-resistant materials.
 15. A multilayered fire-resistant piping material, comprising a tubular fire-resistant expandable layer made of a heat-expandable fire-resistant resin composition and a covering layer covering at least one of the outer surface and the inner surface of the fire-resistant expandable layer, wherein the fire-resistant expandable layer is constituted of a fire-resistant resin composition containing heat-expandable graphite having a 1.3-time expansion temperature of 180 to 240° C. in an amount of 1 to 15 parts by weight based on 100 parts by weight of a polyvinyl chloride-based resin; and the covering layer is constituted of a polyvinyl chloride-based resin composition not containing heat-expandable fire-resistant materials.
 16. The multilayered fire-resistant piping material according to any one of claims 9 to 15, wherein when the piping material is constructed so as to pass through a flooring material and is subjected to a fire-resistant test (complying with ISO 834-1) in which the underside of the floor is heated under conditions that one end of the piping material is exposed to a heating side by 300 mm from the surface on the heating side of the flooring material and that the other end of the piping material is exposed to a non-heating side by 800 mm from the surface on the non-heating side of the flooring material, a pipe inner cross-sectional area S1 at the end of the piping material before burning on the heating side and a pipe inner cross-sectional area S2 at a minimum inner diameter of the piping material after burning satisfy a relationship: (S2/S1)×100≦50.
 17. The multilayered fire-resistant piping material according to any one of claims 9 to 15, wherein the covering layer is provided on each of the outer surface and the inner surface of the fire-resistant expandable layer. 